The utilization of-PAs and NPs to expand the supply of traditional physician services to the public, at reduced costs, as proposed by President Nixon in 1971, has in 1994 become a national mandate. There is an increasing demand for the "traditional" physician services, which can be efficiently and cost effectively performed by nonphysician practitioners, such as PAs and NPs. Statutory changes permitting physicians "to delegate medical acts in an innovative manner" have been, at times, agonizingly slow. However, when compared to the NP statutes, the PA statutes have evolved at a rapid rate. It is postulated that this may be due to the fact that PAs who are totally dependent on physician supervision are more controllable and hence more acceptable to organized medicine than NPs who are currently flexing their political muscles in a quest for greater independence in their performance of traditional physician services. The reimbursability of the two professions is yet another important consideration. Nurse practitioners are "directly" reimbursed by third-party payors, such as Medicare and Medicade, for the traditional physician services they perform, while PA third-party reimbursement is, by law, paid directly to the employing physician or medical facility. Unlike NPs, PAs were conceived by organized medicine, the AMA, to provide a mechanism for physicians to expand their capability to treat increasing numbers of patients. Accordingly, PAs are tied to their supervising physician by the same governmental agencies that regulate physician licensure. Conversely, NPs, who derive their authority to practice from the various state nurse practice acts, have been, at times, impeded in their quest for an enlargement of their scope of practice, including independent prescriptive privileges. The NP bid for greater independence and enlargement of their scope of practice, on a national level, is viewed by organized medicine as an encroachment into the "independent" practice of medicine under the guise of providing advanced nursing care. Unlike PAs, whose professional existence depends on the supervision of a licensed physician, NPs are, by and large, independent of physician control by virtue of their status as licensed members of the nursing profession. While PAs and NPs were once thought to be virtually interchangeable, the divergence of the two professions over the past two decades has been such that all similarities have, for all intents and purposes, disappeared.(ABSTRACT TRUNCATED AT 400 WORDS)