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Medical Laboratory Scientist, MLS(ASCP)
The MLS(ASCP) certification examination of the American Society for Clinical Pathology Board of Certification (ASCP BOC) assesses the full range of clinical laboratory testing knowledge in blood banking, chemistry, hematology, immunology, microbiology, urinalysis/body fluids, and laboratory operations; the same exam is also taken by international candidates for the MLS(ASCPi) credential.
Official exam siteJump to prep options ↓
Questions100 questions
Testing time2 hours 30 minutes
ScoringMinimum passing score of 400 on the ASCP BOC scaled score range (criterion-referenced computerized adaptive testing)
Exam feeUSD 260 non-refundable application fee (MLS(ASCP) and MLS(ASCPi)); reduced pricing available for applicants educated and residing in low-to-middle income countries
Prep options
Study resources for MLS(ASCP)
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Exam overview
What to know before choosing your prep
- Who runs it
- ASCP BOC
- Category
- Medical Laboratory
- Current version
- MLS(ASCP)/MLS(ASCPi) Examination Content Guideline, revised June 9, 2026
- Where it applies
- Global
- Exam languages
- English
- Score scale
- 100–999
- Testing provider
- Pearson VUE
- Format
- Multiple choice with four answer options, one correct answer; computer adaptive test (CAT) administered at Pearson VUE test centers
- Availability
- By appointment at Pearson VUE test centers within the eligibility period stated in the Admission Notification; appointments may be made up to one business day in advance
- Results
- Score notification emailed within four business days after testing (official score report in ASCP account)
- Remote testing
- Not available
Exam structure
100 multiple-choice items (one best answer), delivered by computer adaptive testing, spread across seven content areas with published percentage bands: Blood Banking (17–22%), Chemistry (17–22%), Hematology (17–22%), Microbiology (17–22%), Immunology (5–10%), Urinalysis and Other Body Fluids (5–10%), and Laboratory Operations (5–10%).
Where rules vary
One exam with two credential categories: MLS(ASCP) and the international MLS(ASCPi); delivered worldwide at Pearson VUE test centers, with reduced pricing for low-to-middle income countries
Eligibility
Must satisfy one of the published eligibility routes — e.g., baccalaureate degree from an accredited college/university AND successful completion of a NAACLS-accredited Medical Laboratory Scientist program within the last 5 years; other routes combine a baccalaureate with specified coursework and 1–5 years of acceptable clinical experience (ASCPi routes for internationally educated applicants)
Retake policy
Examination may be taken five times under one eligibility route; after five unsuccessful attempts under one route the applicant must meet the requirements of an alternate route; a new application and full application fee are required for each attempt