Physician assistants (PAs) provide healthcare services with supervision by physicians. Unlike medical assistants, who perform routine clinical and clerical tasks, PAs are medically trained to provide diagnostic, therapeutic, and preventive healthcare services, as delegated by a physician. Working as members of the healthcare team, they take medical histories, examine patients, order and interpret laboratory tests and X-rays, and make diagnoses. They also treat minor injuries by suturing, splinting, and casting. PAs record progress notes, instruct and counsel patients and order or carry out physical therapy. In most states, physician assistants may prescribe medications. PAs may also have managerial duties.

Physician assistants always work with the supervision of a physician. However, PAs may provide care in rural or inner-city clinics where a physician is present for only one or two days each week, conferring with the supervising physician and other medical professionals as needed or required by law. PAs may also make house calls or go to hospitals and nursing homes to check on patients and report back to the physician. The duties of physician assistants are determined by the supervising physician and by state law.