ASCP Histotechnologist (HTL) Practice Test

Prepare for your test with realistic questions.

The ASCP Histotechnologist (HTL) Exam is administered by the American Society for Clinical Pathology Board of Certification (ASCP BOC), an independent certification agency that provides the gold standard of certification for laboratory professionals both in the US and around the world.

Click “Start Test” above to take a free HTL practice test, and check out our premium-quality HTL test prep resources by clicking the links below!

About the ASCP HTL Exam

The HTL Exam is recommended for aspiring histotechnologists that wish to be certified nationally as a means toward gainful employment.

Note that the Histotechnologist (HTL) Exam is different than the Histotechnician (HT) Exam. Click below to learn about the HT exam.

The HTL exam is composed of 100 multiple-choice questions to be answered within a 2.5-hour time limit. The exam is administered using the computer-adaptive testing (CAT) format. Because of this, there is no fixed number of questions or set percentage of the exam you must answer correctly to pass. You only need to answer enough questions correctly to go beyond a certain passing point. As long as your score is above the said passing point, then you will pass the exam.

The exam questions that may be presented will either be theoretical or procedural. Theoretical questions test the skills needed to apply knowledge, calculate results, and correlate reactions/patient results to histology. Procedural questions, on the other hand, measure the skills necessary to perform appropriate laboratory methods and follow quality assurance protocols. Regulatory questions that are based on US sources (e.g., AABB, FDA, CLIA, etc.) will also be asked in the examination.

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ASCP HTL Exam Eligibility

The ASCP offers four eligibility routes for the exam.

Route 1 requires you to have obtained a baccalaureate degree from a college or university that is regionally accredited, and you must have accrued 30 semester hours in chemistry and biology, either within or in addition to your degree. You must also have successfully completed a Histotechnologist program accredited by the National Accrediting Agency for Clinical Laboratory Science (NAACLS) within the last five years.

Route 2 requires you to have obtained a baccalaureate degree with a major in chemistry or biological science from a college or university that is regionally accredited. You must also have accrued one year of full-time clinical experience in a histopathology lab within the past five years OR one year of full-time research, industry, or veterinary experience in a histopathology lab within the past five years.

Route 3 requires a valid HT(ASCP) certification and a baccalaureate degree from a college or university that is regionally accredited. You must also have accrued six months’ worth of the experience listed in Route 2.

Route 4 requires you to have obtained a baccalaureate degree from a college or university that is regionally accredited, and you must have accrued 30 semester hours in chemistry and biology, either within or in addition to your degree. You must also have successfully completed a 50-week histotechnician training course administered by the US military within the last 10 years.

ASCP HTL Exam Outline

The exam is split into five sections, each covering various aspects of histotechnology:

  1. Fixation (15%-25%)
  2. Processing (10%-20%)
  3. Embedding/Microtomy (15%-25%)
  4. Staining (30%-40%)
  5. Laboratory Operations (10%-15%)

Each content area will test your knowledge in handling tissues, demonstrating procedures, setting parameters, and/or using the proper materials and instrumentations in the context of each content area. They will also assess your abilities in laboratory operations, procedures, equipment use, and safety protocols. Note that all BOC exams, including this one, use conventional and SI units for results and reference ranges.

You will also be tested on your knowledge of reagents and dyes to use in the staining process. In addition, the Histotechnologist exam will include questions about basic immunology principles, including antigen retrieval and immunohistochemistry staining theory.

Here’s a closer look at the procedures that appear on each section of the exam:

I. Fixation (15%-25%)

  • Light microscopy
  • Electron microscopy
  • Special stains
  • Frozen sections/tissues
  • Enzyme histochemistry
  • Immunofluorescence
  • Immunohistochemistry
  • Artifacts, precipitates, and pigments
  • Quality control
  • Cytologic specimens
  • In situ hybridization

II. Processing (10%-20%)

  • Light microscopy
  • Frozen sections and tissues
  • Enzyme histochemistry
  • Calcified/decalcified tissue
  • Immunohistochemistry
  • Immunofluorescence
  • Quality control
  • Cytologic specimens (cell blocks, touch preps, etc.)
  • In situ hybridization

III. Embedding/Microtomy (15%-25%)

  • Paraffin
  • Frozen section
  • Gelatin and adhesive
  • Quality control
  • Preparation for molecular testing

IV. Staining (30%-40%)

  • Nucleus/cytoplasm (e.g., H&E)
  • Bone marrow
  • Carbohydrates
  • Connective/supporting tissue
  • Lipids
  • Microorganisms
  • Nerve
  • Pigments, minerals, and granules
  • Tissues and cells, as well as their components (fibrin, mast cells, etc.)
  • Enzyme histochemistry
  • Immunochemistry
  • Quality control
  • Preliminary screening of histochemical special stains
  • Cytological stains (e.g., Papanicolaou)
  • In situ hybridization (FISH, CISH)

Click below to see a list containing the majority of the stains you will encounter on the HTL exam.

  • Alcian blue
  • Alcian blue-PAS
  • Alcian yellow
  • Bielschowsky
  • Carbol-fuchsin (Kinyoun, Ziehl-Neelsen, Fite, auramine-rhodamine)
  • Colloidal iron
  • Congo red
  • Crystal violet
  • Enzyme histochemistry (ATPase, cytochrome oxidase, succinic dehydrogenase, NADH, esterase, acid phosphatase)
  • Fontana-Masson
  • Giemsa
  • Gram
  • Grocott/Gomori methenamine-silver (GMS)
  • Melanin bleach
  • Hematoxylin & eosin (H&E)
  • Immunohistochemical stains
  • Immunofluorescence
  • In situ hybridization (FISH, CISH)
  • Luxol fast blue (LFB/cresyl echt violet)
  • Movat pentachrome
  • Mucicarmine
  • Oil red O
  • Papanicolaou
  • PAS-digestion (PASD)
  • PAS-hematoxylin (PASH)
  • Periodic acid-methenamine silver (PAMS)/Jones
  • Periodic acid-Schiff (PAS)
  • Prussian blue (iron)
  • Reticulin/reticulum
  • Rhodanine
  • Romanowsky
  • Spirochete (Steiner and Steiner, Warthin-Starry)
  • Toluidine blue
  • Trichrome (Gomori, Masson)
  • Verhoeff-van Gieson (VVG)
  • von Kossa

V. Laboratory Operations (10%-15%)

There are no procedural questions on this section of the HTL exam. However, you will be tested on your ability to apply laboratory mathematics. Specifically, the questions will cover the metric system, percent solutions and dilutions, and molar solutions.

exam outline for the Histotechnologist exam, which contains 100 multiple-choice questions and has a time limit of 2.5 hours

ASCP HTL Exam Registration

To register online, you must first create an ASCP account. Since you will be receiving important communication regarding your exam through your specified email, be sure that you have used a valid email address when creating your account.

You must submit your online application and pay the necessary $250 application fee either through the mail with a check or money order or by credit card within 30 days of the date you started your application. Your application will not be processed until the payment has been received and processed.

After this, you must submit the required documentation to support your eligibility, including training certifications, accomplished experience forms, letters, official transcripts, etc. All documents must be in PDF format and must contain original, handwritten signatures; digital signatures are not allowed. It is recommended that you submit these electronically through the ASCP website.

Applications will be processed within 60 business days, and you must submit your supporting documents within 45-60 business days from the submission of your application.

Once your application is accepted, you will receive a notification email allowing you to schedule an appointment for the exam at the affiliated Pearson VUE website. Be sure to take the examination within the period specified on your admission notification. If you cancel your exam or fail to appear during your said appointment, you will have to reapply to take the exam and pay the full application fee again. You are able to reschedule at least 24 hours in advance.

Test Day

You must arrive at the test venue 30 minutes before your scheduled exam time. During check-in, Pearson VUE will collect your signature and photo. They will also use biometric technology to capture a palm-vein image, which ensures that each examinee only has a single record in the system to safeguard the integrity of the exam.

You will need to bring a form of valid government-issued identification that contains your photo, signature, and a name that matches the name you used when applying for the exam.

You will have to leave your personal belongings in a small locker outside the testing room, including your smartphone and smartwatch. You are, however, allowed to bring a non-programmable calculator.

Histotechnologist Exam Scores

How the Exam is Scored

The HTL exam is computer-adaptive, so depending on your performance, the difficulty of your test will increase or decrease as you go on.

Here’s a look at how it works:
A flowchart that shows the adaptive nature of the exam

The first question is judged to be of medium difficulty, and depending on your performance, the next question may be easier or harder. If you do well in the first question, the second question will be harder; conversely, if you do poorly on the first question, the second question will be easy.

The questions on the HTL exam are rated on a scale of 100-999. The higher a question is rated, the harder the question is (e.g., a question marked as 483 will be easier than a question marked 552).

To pass the exam, your final question must be on or above the 400 mark. If your final question is below the 400 mark, you will not pass the exam, even if you have answered some questions above the 400 mark at some point during the exam. This is because the computer has rated the difficulty of your final question based on how you answered the previous questions.

Receiving Your Scores

You should receive a notification email within 4-7 business days stating that your scores are ready to view. You must then log in to your ASCP account to view if you have passed or failed the exam.

If you completed a NAACLS-, ABHES-, or CAAHEP-accredited program, your score will also be released to the officials of your program unless you provide written consent stating otherwise to the ASCP Board of Certification.

You will receive a wall certificate sent to the main address on your application within a few months if you passed the exam. You may also request to send a verification of your certification to a third party that requests it, such as an employer or your state licensing board. This certificate is valid for three years.

Retaking the ASCP HTL Exam

If you fail the exam, you can retake the exam four times under one of the eligibility routes. Take note that you must pay the full application fee for every retake, and you must remember that your laboratory experience must be within the required time limit from the date of application.

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How to Pass the HTL Exam

How to Study Effectively

Your success on HTL test day depends not only on how many hours you put into preparing but also on whether you prepared the right way. It’s good to check along the way to see whether your studying is paying off. One of the most effective ways to do this is by taking HTL practice tests to evaluate your progress. Practice tests are useful because they show exactly where you need to improve. Every time you take a free HTL exam practice test, pay special attention to these three groups of questions:

  • The questions you got wrong
  • The ones you had to guess on, even if you guessed right
  • The ones you found difficult or slow to work through

This will show you exactly what your weak areas are and where you need to devote more study time. Ask yourself why each of these questions gave you trouble. Was it because you didn’t understand the material? Was it because you didn’t remember the vocabulary? Do you need more repetitions on this type of question to build speed and confidence? Dig into those questions and figure out how you can strengthen your weak areas as you go back to review the material.

Answer Explanations

Additionally, many Histotechnologist practice tests have a section explaining the answer choices. It can be tempting to read the explanation and think that you now have a good understanding of the concept. However, an explanation likely only covers part of the question’s broader context. Even if the explanation makes sense, go back and investigate every concept related to the question until you’re positive you have a thorough understanding.

Comprehend Each Topic

As you go along, keep in mind that the Histotechnologist practice test is just that: practice. Memorizing these questions and answers will not be very helpful on the actual test because it is unlikely to have any of the same exact questions. If you only know the right answers to the sample questions, you won’t be prepared for the real thing. Study the concepts until you understand them fully, and then you’ll be able to answer any question that shows up on the test.

Strategy for Histotechnologist Practice

When you’re ready to start taking practice tests, follow this strategy:

  • Remove Limitations. Take the first test with no time constraints and with your notes and Histotechnologist study guide handy. Take your time and focus on applying the strategies you’ve learned.
  • Time Yourself. Take the second practice test “open book” as well, but set a timer and practice pacing yourself to finish in time.
  • Simulate Test Day. Take any other practice tests as if it were test day. Set a timer and put away your study materials. Sit at a table or desk in a quiet room, imagine yourself at the testing center, and answer questions as quickly and accurately as possible.
  • Keep Practicing. Keep taking practice tests on a regular basis until you run out of practice tests or it’s time for the actual test. Your mind will be ready for the schedule and stress of test day, and you’ll be able to focus on recalling the material you’ve learned.



How many questions are on the exam?


The Histotechnologist Exam contains 100 questions.


How long is the exam?


The Histotechnologist Exam has a time limit of 2.5 hours.


What is a passing score?


There is no set passing score for the HTL exam. To pass, the computer must serve you a question with a difficulty rating of at least 400 as your final question.

Learn more about how the Histotechnologist exam is scored.


When will I receive my scores?


Your HTL scores will be available on the ASCP website within 4-7 business days after completing the exam.


How much does the exam cost?


The HTL exam costs $250.

By Kate Nockunas

Kate has been Mometrix’s Nursing and Medical Editor for over four years. She has a bachelor’s degree in Communications from Vanderbilt University, a bachelor’s degree in Nursing from Marymount University, and a master’s degree in Education from Johns Hopkins. Kate is a critical care registered nurse who still works occasionally in the ICU and PACU.


by Mometrix Test Preparation | This Page Last Updated: January 9, 2024