ASCP MLS
Offered by ASCP Board of Certification (BOC)
MLS(ASCP) is the American Society for Clinical Pathology Board of Certification exam for Medical Laboratory Scientists. It is a computer-adaptive test of 100 multiple-choice questions in 2 hours 30 minutes covering blood bank, chemistry, hematology, microbiology, immunology, urinalysis/body fluids, and laboratory operations.
EXAM AT A GLANCE
Format
100
Testing time
30
minutes
Sections
7
Delivery
Pearson VUE test centers
Passing score
400
Cost
$260 USD non-refundable application fee (MLS(ASCP); reduced pricing may apply in some countries)
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What the exam covers
Blood banking
17–22%
Chemistry
17–22%
Hematology
17–22%
Microbiology
17–22%
Urinalysis and other body fluids
5–10%
Immunology
5–10%
Laboratory operations
5–10%
About the ASCP MLS certification
The scaled passing score is 400 on a 100–999 scale. You must answer each item to continue; skipping is not allowed. Several education and experience routes exist — Route 1 is typically an NAACLS-accredited MLS program plus a baccalaureate degree.
Who it’s for
Clinical laboratory science graduates and experienced laboratorians seeking MLS(ASCP) certification for hospital and reference-lab roles.
- Format
- 100 multiple-choice questions, computer adaptive (CAT); one best answer; items cannot be skipped
- Testing time
- 2 hours 30 minutes
- Passing score
- 400 on a 100–999 scaled scale
- Validity
- Certification Maintenance Program (CMP) on a 3-year cycle
- Prerequisites
- Meet one published BOC route (accredited MLS program, or degree plus clinical experience/categorical certifications — see current route chart)
Official exam page· Details verified September 2026
Exam details can change. Always confirm current requirements, fees, and exam policies with the certification provider before registering.
How to prepare
01
Download the current MLS content guideline and study the seven content percentages, not a random Q-bank order.
02
Rotate blood bank, chem, heme, and micro weekly — each is about one-fifth of the exam.
03
Practice calculations and result correlation (disease states) rather than only instrument menus.
04
Take CAT-style practice: you cannot skip, so build a first-answer discipline.
05
File the application with documentation early; the $260 fee is non-refundable and routes are audited.
FAQ
What is the ASCP MLS passing score?
A scaled score of 400 on the 100–999 scale. There is no published raw percentage because CAT difficulty adapts.
Is MLS the same as MLT?
No. MLT(ASCP) is a separate technician-level exam. MLS is the scientist-level credential with a different content outline and eligibility routes.
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