Objective. To describe the characteristics of visits to physician assi
stants (PAs) and nurse practitioners (NPs) in hospital outpatient depa
rtments in the United States. Methods, Data from the 1993 and 1994 Nat
ional Hospital Ambulatory Medical Care Surveys were used to compare ho
spital outpatient department visits in which the patient was seen by a
PA or NP, or both, with outpatient visits to ail practitioners. Resul
ts, An average of 64 million annual outpatient visits were made in 199
3-1994, and patients were seen by PAs, NPs, or both, at 8% of these vi
sits. PA-NP visits were more likely than total visits to occur in the
Mid west, in non-urban areas, and in obstetric-gynecology clinics, and
a higher proportion involved patients younger than age 25. Smaller di
fferences were found between PA-NP visits and total outpatient visits
in ''reason for visit,'' ''principal diagnosis,'' and ''medication pre
scribed.'' Conclusion, Beyond the care they provide in physicians' off
ices and other non-hospital settings, PAs and NPs make an important co
ntribution to ambulatory health care delivery in hospital outpatient d
epartments.