Physician assistants are health care professionals licensed to practice medicine with physician supervision. As part of their comprehensive responsibilities, PAs conduct physical exams, diagnose and treat illnesses, order and interpret tests, counsel on preventive health care, assist in surgery, and in virtually all states can write prescriptions. Within the physician-PA relationship, physician assistants exercise autonomy in medical decision-making and provide a broad range of diagnostic and therapeutic services. A PA's practice may also include education, research, and administrative services.

PAs are trained in intensive education programs accredited by the Accreditation Review Commission on Education for the Physician Assistant (ARC-PA).

Because of the close working relationship the PAs have with physicians, PAs are educated in the medical model designed to complement physician training. Upon graduation, physician assistants take a national certification examination developed by the National Commission on Certification of PAs in conjunction with the National Board of Medical Examiners. To maintain their national certification, PAs must log 100 hours of continuing medical education every two years and sit for a recertification every six years. Graduation from an accredited physician assistant program and passage of the national certifying exam are required for state licensure.