Distribution of health problems encountered by nurse practitioners and physicians in general/adult medicine clinics was studied. Proportional samples by clinics were selected from a total of 13,039 patient visits made to four clinics during an 18-week period in 1978. A Patient Encounter Form was used as the instrument and the ICD-9-CM as the coding system. Results showed that (a) 25.1% of the 13,039 patient visits were made to the nurse practitioners and 74.9% to the physicians, (b) 23 frequently reported health problems constituted more than 50% of all health problems seen by both provider groups, and (c) health problems with V codes constituted less than 30% of all health problems seen by both provider groups. Many similarities in health problems seen by nurse practitioners and physicians may indicate that nurse practitioners in the general/adult medicine specialty are used more to substitute for physicians in managing selected health problems than to complement medical practice.