Context: Physician assistants (PAs) and nurse practitioners (NPs) have licensure to practice in all states and they have prescriptive authority in 47 and 40 states, respectively. However, there have been no published studies from a national standpoint comparing urban and rural settings. Purpose: The objective of this study was to describe the characteristics of providers, patients, and the type of prescriptions written by PAs and NPs and to compare these activities to those of physicians in metropolitan and nonmetropolitan settings. Methods: The National Ambulatory Medical Care Survey was used to analyze a representative sample of 149,202 visits to primary care physician offices over a 6-year period (1997-2002) in which a prescription was written by a PA, NP or physician. Results: A PA or NP was the provider of record for 3% of the primary care visits. The 3 providers wrote prescriptions for 60% to 70% of all visits, and the mean number of prescriptions was 1.3 to 1.5 per visit (range 0-5), depending on the provider. PAs were more likely to prescribe a controlled substance than were physicians or NPs (19.5%, 12.4%, 10.9% respectively). Only in rural areas did differences emerge. In rural areas, NPs wrote significantly more prescriptions than physicians and PAs, and PAs wrote significantly fewer prescriptions than the other providers. Conclusions: Overall, PAs and NPs are prescribing in a manner similar to physicians in the type of medications used in their patient management. In nonmetropolitan areas, prescribing differences among the 3 types of providers bear further exploration.