The AAB Medical Laboratory Evaluation (AAB-MLE) program provides Proficiency Testing (PT) service to over 5,900 private and public clinical laboratories, both here in the US and abroad. As a service of the American Association of Bioanalysts, a professional society serving the clinical laboratory community and those involved in clinical laboratory operation, AAB-MLE offers user-friendly PT across the majority of laboratory specialties, including hematology, chemistry, microbiology, embryology, andrology, and immunology.

AAB-MLE is the new combination of two long-standing Proficiency Testing programs. In 1949, Dr. Nell Hollinger, a founding member of the American Association of Bioanalysts, began one of the world’s first proficiency testing programs for clinical laboratories. Its goal was to offer comprehensive external quality control programs for the betterment of laboratory testing results. Medical Laboratory Evaluation Proficiency Testing began in 1973 as a collaborative effort between the College of American Pathologists (CAP), the Proficiency Evaluation Program (PEP), and the American Society of Internal Medicine (ASIM) as a way for laboratories to assess the quality of their testing results. Developed as an educational tool, PT was initiated to help laboratories investigate any internal procedural problems so that corrective action could be introduced before patient results are affected.

Combined, AAB-MLE has provided some form of PT service for over 73 years. Our technical support staff includes seven medical laboratory science professionals, with over 100 years of combined laboratory experience. We have two staff members with Master of Science degrees and one PhD. Our customer service staff members all have 5+ years of experience helping our participants with ordering or troubleshooting questions. As such, AAB-MLE is able to help laboratorians navigate the ever-changing world of clinical testing and the stresses encountered by the need to perform and pass proficiency testing. We offer online result reporting, participant summaries, and evaluation reports. Off-schedule/remedial testing is available to any lab at any time (subject to sample availability), regardless of enrollment status with AAB-MLE. Cost-effective modules are available to cover any size physician office laboratory’s test menu, including point of care testing and CLIA-waived tests.

About AAB

American Association of Bioanalysts (AAB) Proficiency Testing is one of the nation’s largest full-service proficiency testing programs, servicing more than 6,500 clinical testing centers. It is approved for all analytes by Clinical Laboratory Improvements Amendments (CLIA), Joint Commission on Accreditation of Healthcare Organizations (JCAHO), Centers for Medicaid and Medicare Service (CMS), COLA, and all state agencies to satisfy proficiency testing requirements.

AAB Proficiency Testing began offering comprehensive external quality control PT programs in 1949. Since then, AAB Proficiency Testing has made comprehensive external quality control programs available to every individual and clinical laboratory wishing to participate. These programs are updated continuously and meet the needs of evolving techniques and concepts in the 21st Century Laboratory.

In May of 1996, AAB Proficiency Testing also made available proficiency testing programs for the clinical laboratory specialties of andrology and embryology.

Our Mission

AAB Proficiency Testing is committed to the pursuit of excellence in clinical laboratory services by enhancing the professional skills of each of its members; promoting more efficient and productive operations; offering external quality control programs; collaborating with other professional associations and government agencies; promoting safe laboratory practices; and educating legislators, regulators, and the general public about clinical laboratory tests and procedures.

About MLE

The mission of MLE, a clinical laboratory evaluation program, is to administer a service-oriented laboratory proficiency testing program that provides technical and educational tools necessary to assess, monitor and improve the quality of laboratory testing.


ACP’s Medical Laboratory Evaluation (MLE) proficiency testing began in 1973 as the Proficiency Evaluation Program (PEP), a collaborative effort between the American Society of Internal Medicine (ASIM), which sponsored the MLE program, and the College of American Pathologists (CAP). When announcing the program, ASIM stated they wanted physicians with office laboratories to have a clinical laboratory evaluation program that assures their patients, personnel and third parties of the quality of test results. The program soon became known as the Medical Laboratory Evaluation (MLE).


MLE introduced significant changes to the proficiency testing program in 1996. In that program year, MLE directly assumed the responsibilities for specimen procurement, data processing and the production of evaluation reports. Investing in sophisticated computer software increased efficiency in order processing, while state-of-the-art optical scanning technology improved data summarization—expediting the turnaround of accurate and easy-to-understand evaluations.

In the past, the MLE program primarily has provided service to physician office laboratories (POLs). MLE broadened its focus with the 1998 program year, emphasizing a specific mission: “…to administer a service-oriented proficiency testing program that provides the technical and educational tools necessary for participants to assess, monitor and improve the quality of their laboratory testing.” While continuing its commitment to service and education for POLs, MLE also extended its services to small hospital laboratories. MLE has offered more analytes and increased module configurations to accommodate the more extensive testing menus of these laboratories.Additionally, ASIM announced their merger with the American College of Physicians (ACP) as of July 1, 1998. The new organization became known as ACP-ASIM. As a result of the merger, MLE will be able to expand our educational resources and provide our participants with more technical information, emphasizing issues that contribute to accurate patient testing.


In 2003, ACP-ASIM became simply ACP (American College of Physicians). Medical Laboratory Evaluation (MLE) is a program provided by American College of Physicians.