MLS (ASCP) – Medical Laboratory Scientist

A medical laboratory scientist (MLS) is a qualified and certified professional who performs a variety of high-complexity analytical tests. They work closely with physicians to help accurately diagnose patient health conditions. You may also hear an MLS referred to as a clinical laboratory scientist (CLS) or medical technologist (MT).

To become a medical laboratory scientist, you must earn the MLS (ASCP) credential, awarded by the American Society for Clinical Pathology Board of Certification (ASCP BOC). This certification confirms that you have met the eligibility requirements and passed the BOC exam.

Here is the quick video for MLS (ASCP). If you prefer watching over reading, then start here?

U.S. candidates typically pursue the MLS (ASCP) credential, while international candidates may qualify for the MLS (ASCPi) credential. At MLSi Academy, we offer tailored support for both groups, with a strong focus on helping U.S. candidates meet their certification and licensing goals.

The ASCP Board of Certification (BOC) is recognized globally as the gold standard for medical laboratory professionals. Earning an MLS credential through the ASCP BOC brings specific eligibility requirements, preparation strategies, and career benefits, all of which we’ll cover in this guide.

What Is MLS ASCP Certification?

MLS (ASCP) stands for Medical Laboratory Scientist certified by the American Society for Clinical Pathology Board of Certification.

This credential shows that a lab professional has passed the ASCP BOC exam and meets the professional standards required to work in clinical laboratories. Candidates need a minimum score of 400 out of a possible 999 to pass this exam and earn the credential.

After earning the certification, many professionals choose to keep it active by joining the ASCP’s Credential Maintenance Program (CMP). When they do, a small “CM” is added to the end of their credential like this: [MLS(ASCP)^CM].

The CMP requires certified professionals to renew every three years by completing a set number of continuing education (CE) hours.

What’s the Difference Between MLS (ASCP) and MLS (ASCPi)?

The American Society for Clinical Pathology Board of Certification (ASCP BOC) offers both credentials to medical laboratory scientists worldwide.

The MLS (ASCP) is meant for U.S. medical laboratory scientists (U.S. citizens) who hold a degree from a U.S. institution. On the other hand, the MLS (ASCPi) is for international medical laboratory professionals who do not have a U.S. degree.

That’s why MLS (ASCPi) candidates must get a U.S. degree equivalency or evaluation of their academic credentials from an evaluation agency approved by the ASCP BOC, as explained earlier in this post.

Everything else,  including the curriculum or syllabus, is the same for both certifications.

Both exams use both conventional and SI units for lab results and reference ranges.

Benefits of Earning the MLS (ASCP) Certification by BOC

Before earning your credential from the largest certification body in clinical pathology and laboratory science,  the ASCP Board of Certification (ASCP BOC®),  consider the following advantages:

1. ASCP BOC® is recognized globally as the gold standard for certification in the field of laboratory medicine.
2. The American Board curriculum is among the most current and advanced in clinical and laboratory sciences. It covers the latest developments and findings in medical analysis.
3. The MLS (ASCP) credential is widely regarded as the most respected and valuable certification for laboratory professionals.
4. As a certified MLS (ASCP), you meet the requirements to apply for a medical laboratory license in any U.S. state.
5. In many U.S. states and other countries, the ASCP BOC® certification can directly grant you the license to practice without the need for additional exams.

Routes to MLS (ASCP) Certification (for U.S. Candidates)

To qualify for MLS (ASCP) certification, U.S. candidates must meet the education and experience requirements under one of the approved routes below:

Route 1:

• Successful completion of a NAACLS-accredited MLS program within the last five years.
• Bachelor's degree from an accredited regional or national U.S. college or university.

Route 2:

• Valid MLT (ASCP) certification.
• Bachelor's degree from an accredited regional or national U.S. college or university.
• 16 semester hours in biology (including one semester of microbiology).
• 16 semester hours in chemistry (including one semester of biochemistry or organic chemistry).
• Two years of clinical lab experience within the last five years in blood banking, body fluid analysis, hematology, and microscopy.

Route 4:

• A Bachelor's degree from an accredited educational institution,
• AND successful completion of a two-year Medical Laboratory Science program including blood banking (immunohematology), chemistry, hematology, and microbiology.

Route 4 Requirements:

• Bachelor's degree from an accredited regional or national U.S. college or university.
• 16 semester hours in biology (including one semester of microbiology).
• 16 semester hours in chemistry (including one semester of biochemistry or organic chemistry).
• Five years of clinical lab experience within the last ten years.

Route 6:

• Completion of a 50-week U.S. military medical laboratory training program within the last ten years.
• Bachelor's degree from an accredited regional or national U.S. college or university.
• 16 semester hours in biology (including one semester of microbiology).
• 16 semester hours in chemistry.

Routes to MLS (ASCPi) Certification (for International Candidates)

Route 1:

• A bachelor’s degree in Medical Laboratory Science, biology, or chemistry
• Successful completion of a structured lab training program covering blood banking, chemistry, hematology, and microbiology

Route 2:

• A bachelor’s degree in Medical Laboratory Science
• Three years of clinical lab experience in the core areas: blood banking, chemistry, hematology, and microbiology

Route 3:

• A bachelor’s degree from an accredited institution
• Completion of a two-year Medical Laboratory Science program that includes blood banking(immunohematology), chemistry, hematology, and microbiology

Route 4:

• A bachelor’s degree in biological science or chemistry (often applies to graduates of medicine, veterinary medicine, Science and Pharmacology)
• Five years of clinical experience in blood banking, chemistry, hematology, and microbiology from a licensed laboratory.

Route 5:

• Bachelor's degree from an accredited educational institution
• Two-year diploma from an accredited/approved* educational institution in biological science or chemistry
• Five years of clinical experience in blood banking, chemistry, hematology, and microbiology

Am I Eligible for MLS ASCP

Here at MLSi Academy, we use Route 4 (The Most Common Path) as a model to help you check your eligibility for the BOC Exam.

For a step-by-step guide on how to check your MLS (ASCP) exam eligibility, read this post.

About the ASCP MLS Exam

Once you’ve confirmed your eligibility, the next step is to sit for the MLS (ASCP) exam. The exam is administered by the ASCP Board of Certification and follows a specific format you’ll want to be familiar with.

Here’s what to expect:

• The exam includes 100 multiple-choice questions.
• You’ll have 2.5 hours to complete it.
• The format uses Computer Adaptive Testing (CAT), which adjusts the difficulty of questions based on your answers. If you answer a question correctly, the next one may be slightly harder; if you answer incorrectly, the next one may be easier. This approach helps measure your knowledge more accurately than a fixed-form test.
• To pass, you must achieve a minimum score of 400 out of a possible 999. Once you reach that benchmark, you’re officially certified as an MLS (ASCP).

“With CAT, when an examinee answers a question correctly, the next test question has a slightly higher level of difficulty. The difficulty level of the questions presented to the examinee continues to increase until a question is answered incorrectly. Then a slightly easier question is presented. In this way, the test is tailored to the individual’s ability level.”

ASCP BOC

MLS ASCP Study Guide & Exam Questions

The MLS Study Guide is a PDF file compiled by the ASCP BOC to help ASCP candidates understand the exam curriculum. It outlines the key subject areas you should review before taking the MLS exam.

According to ASCP, the exam includes seven core subject areas:

• Blood Bank
• Microbiology
• Chemistry
• Hematology
• Urinalysis and other bodily fluid
• Immunology
• Laboratory Operation

Study Questions

Every question on the test connects back to one of these areas. But keep in mind that these aren’t simple recall questions. The ASCP BOC likes to test your ability to apply knowledge in real-world lab settings. So expect questions that are tricky, detailed, and not always straightforward.

Study Material

Don’t just read; train your brain. The best way to prepare is to use study material that explains concepts clearly and mimics the kind of questions you’ll face on the exam. If you’re jumping between multiple sources or just focusing on theory without practice, you’ll waste valuable time and energy.

Reading List

ASCP recommends about 48 reading lists between textbooks, online journals, and resources to pass your MLS exam. Some of the resources are:

• AACC Clinical Chemistry Trainee Council
• American Association for Clinical Chemistry (AACC)
• Association for the Advancement of Blood & Biotherapies (AABB)
• Blood Bank Guy
• BloodLine Image Atlas
• CellAtlas – Blood Cell Morphology Guide
• CDC
• DPDx – CDC Parasitology Diagnostic Web Site
• AACC Laboratory Medicine Practice Guidelines
• Clinical Laboratory Science
• Medical Laboratory Observer
• Lab Medicine

How to Become MLS ASCP Certified

If you’re aiming to earn the MLS (ASCP) credential from the ASCP BOC, MLSi Academy is here to guide you through each step and help you stay on track. Here’s how to get started:

✅ Certification Process:

1. Check your eligibility: Review the approved MLS (ASCP) routes listed above to confirm you meet the education and experience requirements.
2. Get official copies of your academic certificates from your university.
3. Complete any additional requirements. Depending on your route, you may need to verify MLT certification or clinical lab experience.
4. Prepare for the exam. Study using the official ASCP reading list or make it easier with MLSi Academy’s 4×4 MLS ASCP Prep Course, built to save you time and improve your chances of passing.
5. Apply for the BOC exam. For step-by-step application instructions, check [this post].
6. Pay the exam fee.
7. Email a scanned copy of your documents to: ascpinternational@ascp.org
8. Schedule your exam date.
9. Take your exam. Aim for a passing score of 400 or higher to earn your certification.

Once you pass, you’ll officially be a certified Medical Laboratory Scientist (MLS (ASCP))

For more detailed guidance, see our full post on how to get MLS (ASCP) certified.

MLS ASCP Certification Online Programs

If you need additional qualifications to meet the MLS (ASCP) certification requirements, several accredited online programs in the United States can help you get there. These programs are designed to prepare you for both the exam and future licensing across U.S. states.

Some top options include:

George Washington University (Health Sciences)

• Medical Laboratory Sciences Post-Baccalaureate Certificate (ASCP MLS)
• MSHS – Laboratory Medicine (ASCP MLS)
• MSHS in Biomedical Laboratory Science (BLS)
• MSHS in BLS – Medical Laboratory Science

University Of West Florida

• Online BS in Clinical Laboratory Sciences (MLT Certification Required)
• Online BS in Health Sciences

University Of Cincinnati Online

• BS in Medical Laboratory Science (MLT/CLT Certification Required)
• MS in Medical Laboratory Science Leadership

Where to Get MLS ASCP Exam Prep That Works

If you’ve looked around for ASCP prep, you already know the internet is full of scattered resources, confusing advice, and question banks that don’t even match the real exam.

At MLSi Academy, we keep things simple.

Our all-in-one MLS ASCP prep package gives you everything you need to study smart, stay on track, and pass the exam without wasting time or money on extra materials.

Here’s what’s included in the course:

✔️ Live online classes led by certified MLS instructors
✔️ One unified study guide based on the ASCP exam blueprint
✔️ QBank with exam-style questions (tricky ones, just like the real test)
✔️ Class recordings so you can review on your own time
✔️ Direct access to instructors when you need support or clarification
✔️ Mobile app access for studying on the go
✔️ Certificate of completion

You don’t need to piece together study material or second-guess your prep. We’ve already done the heavy lifting, so you can focus on passing.

Frequently Asked Questions About ASCP Certification