Getting a clinical laboratory scientist (CLS) license requires a bachelor’s degree, completion of a clinical training program, passing a national certification exam, and in some states, a separate state license. The full process typically takes five to six years from the start of undergraduate coursework, though the exact timeline depends on which eligibility route you pursue and where you plan to work.
Step 1: Earn a Bachelor’s Degree
Every path to CLS licensure starts with a bachelor’s degree. Your major can vary, but you’ll need heavy coursework in biology and chemistry. The ASCP Board of Certification, which administers the most widely recognized national exam, requires at least 16 semester hours of biology (including microbiology) and 16 semester hours of chemistry (including organic chemistry or biochemistry). Some states set the bar higher. California, for example, requires 18 semester hours of biology that specifically include hematology, immunology, and medical microbiology, plus 3 semester hours of physics covering light and electricity.
If you’re still choosing a degree program, majors in clinical laboratory science, medical technology, biology, or chemistry will naturally cover most of these prerequisites. Planning your coursework early matters because missing even one required class can delay your application by a full semester.
Step 2: Complete a Clinical Training Program
After finishing your degree, you’ll need hands-on clinical training in a hospital or reference laboratory. Programs accredited by the National Accrediting Agency for Clinical Laboratory Sciences (NAACLS) are the gold standard. Graduating from a NAACLS-accredited program gives you the most direct route to sitting for the certification exam, and first-time pass rates for graduates of these programs run around 92%.
Clinical training programs are typically one year of full-time work, structured around 40-hour weeks split between classroom instruction and bench training. At UCSF, for instance, the rotation spans 52 weeks and cycles through every major laboratory department: 11 weeks in chemistry, 9 in microbiology, 8 in hematology, 6 in blood banking (immunohematology), 4 each in urinalysis/body fluids, serology/immunology, and molecular biology, plus shorter rotations in parasitology, phlebotomy, and point-of-care testing. This breadth is intentional. Licensing requires competency across all core areas of the clinical lab, not just one specialty.
These programs are competitive. Many require you to apply for a trainee license or permit before starting, and spots are limited. In California, you must obtain a CLS Generalist training license through the Department of Public Health before beginning your internship.
Step 3: Pass a National Certification Exam
National certification is the credential that unlocks licensure in most states. The two main certifying bodies are the ASCP Board of Certification and American Medical Technologists (AMT). The ASCP’s Medical Laboratory Scientist (MLS) exam is the most widely accepted.
ASCP Eligibility Routes
The ASCP offers several paths to exam eligibility, depending on your background:
- Route 1 (most common): A bachelor’s degree plus completion of a NAACLS-accredited MLS program within the last five years.
- Route 2: A valid MLT (medical laboratory technician) certification, a bachelor’s degree with the required biology and chemistry credits, and two years of full-time clinical lab experience within the last five years.
- Route 4: A bachelor’s degree with the required science coursework and five years of full-time clinical experience within the last ten years. This route exists for experienced lab workers who never completed a formal training program.
- Route 5: For internationally trained scientists holding an MLS(ASCPi) certification, with a transcript evaluation verifying equivalency to a U.S. bachelor’s degree, plus five years of clinical experience.
- Route 6: Completion of a 50-week U.S. military medical laboratory training course, a qualifying bachelor’s degree, and one year of clinical experience.
The ASCP MLS exam costs $260. The fee is nonrefundable regardless of outcome.
AMT as an Alternative
American Medical Technologists offers its own MLS certification for $245. Exams are taken at Pearson VUE testing centers or at your school if that option is available. You’ll need two forms of ID on test day, one with a photo. Results come back immediately after the exam. If you don’t pass, you can retake it after 45 days, with a maximum of four total attempts.
Step 4: Apply for Your State License
This is where the process diverges significantly depending on where you live. Not every state requires a separate license beyond national certification. Some states accept the ASCP or AMT credential alone, while others have their own licensing boards with additional requirements.
California has some of the strictest requirements in the country. Beyond passing the national exam, applicants must complete a 52-week clinical internship (not the shorter programs accepted elsewhere), pass a quiz on California state laboratory law, and apply for licensure through the California Department of Public Health’s Laboratory Field Services division. You’ll need to submit a certificate of training completion and a verification letter from your training facility.
New York requires passing either the MLS(ASCP) or the international equivalent exam, but processes licensure through the State Education Department rather than a health department. Florida, Louisiana, Nevada, Hawaii, and several other states also maintain independent licensing requirements. Before committing to a training program, check the licensing rules in the state where you plan to work. Moving between states later can require additional paperwork or even supplemental exams.
Routes for International Graduates
If you earned your laboratory science degree outside the United States, you can still pursue licensure, but the path involves extra steps. You’ll need a transcript evaluation to verify that your education is equivalent to a U.S. bachelor’s degree. The ASCP offers an international certification, the MLS(ASCPi), specifically designed for professionals trained abroad. From there, Route 5 allows you to qualify for the domestic MLS exam after accumulating five years of full-time clinical experience across all major lab disciplines.
Some states, like New York, explicitly accept the international ASCP exam for licensure. Others may have additional requirements, so researching your target state early saves time and frustration.
Keeping Your License Active
Earning the credential is not a one-time event. The ASCP requires ongoing continuing education through its Certification Maintenance Program (CMP). You’ll earn CMP points through a variety of activities: formal continuing education courses (one contact hour equals one point), college coursework (one semester hour equals 15 points), webinars and online modules, employer-provided training, or even publishing journal articles (five points each) and presenting research posters (two points per poster). No more than half of your required points can come from continuing education courses alone, which pushes you toward a mix of learning activities.
Competency assessments from your employer count for two points per cycle, capped at four. Serving on professional committees or accreditation boards earns three points per year. The program is designed to keep your knowledge current across a field where testing technology, regulations, and best practices shift regularly.
Some states layer their own renewal requirements on top of the national program. California, for instance, manages license renewal through its Department of Public Health on a separate schedule. Staying on top of both your national certification and state license renewal deadlines prevents gaps in your credentials that could interrupt your ability to work.
Realistic Timeline and Costs
For someone starting from scratch, expect four years for a bachelor’s degree followed by one year of clinical training and a few months for exam scheduling and state processing. That puts the total at roughly five and a half to six years. If you’re already a working medical laboratory technician with an MLT certification, Route 2 lets you upgrade to MLS with two years of qualifying experience and the right coursework, potentially shaving years off the process. Route 4 offers a path for experienced lab workers without formal training, though it requires five years of documented full-time experience.
Direct costs beyond your degree include the clinical training program (some are paid positions, others charge tuition), the certification exam ($245 to $260), and state licensing fees that vary by jurisdiction. California’s application and training license fees add several hundred dollars to the total. Budget for continuing education costs in the years that follow, though many employers cover these as part of professional development.