This paper considers medical care given by physicians to men and women in the United States. It asks how often significant sex differences in care occur, and if these differences are attributable to medically relevant factors or not. Sex differences in diagnostic services, therapeutic services, and dispositions for follow-up are studied for All Visits, 15 major groups of complaints, and 5 specific complaints (fatigue, headache, vertigo/dizziness, chest pain, and back pain). Data are from the 1975 National Ambulatory Medical Care Survey (NAMCS). The analysis reveals that medical care is often similar for men and women, but a sizable numbers of significant sex differences occur (about 30 to 40 per cent of the services and dispositions studied), and they tend to show more medical care for women. Most of the differences persist even after controlling for medically relevant factors (patient age, seriousness of problem, diagnosis, prior visit status, and reasons for visit). Notably, women still receive more total prescriptions, and return appointments for many complaint groups. They receive more services for back pain and headaches and more follow-up plans for vertigo/dizziness and back pain. Remaining sex differences may be due to missing medical factors, patient requests for care, patient distress and needs for nurturance, and physician sex bias. In contrast to a recent San Diego study, national data show few significant sex differences in the extent and content of diagnostic services given for five common complaints.