An analysis of one year's data from family practices in Colorado tested the hypothesis that there are no significant differences in the proportion of patients with problems in each of the 18 major International Classification of Health Problems in Primary Care (ICHPPC) categories among visiting patients in rural, urban, and teaching family practices. Four rural, three urban, and five residency practices participated in the study from January 1, 1978, through December 31, 1978. Transient patients were excluded. There were 25,525 patients included in the study. Each setting was compared with the other two settings in each of the 18 ICHPPC categories. More than half of the comparisons differed at the .001 significance level, and the setting with a significantly greater proportion of visiting patients with diseases in a given category was identified. These differences may have implications for disease surveillance, the planning for delivery of primary health care in different settings, and the preparation of health care providers for practice.