Five hundred twenty new patients were randomly and prospectively assigned to receive care in the Internal Medicine Clinic or Family Practice Clinic of a large university hospital. Previous analyses of outpatient data demonstrated that the frequency of visits to the clinic of primary care, acute care clinic, emergency room, and consultant clinics were all significantly higher for patients randomized to internal medicine compared with family practice. In the present study, patients' charts were reviewed for information regarding hospitalizations. During the 3.4-year study period, there were a total of 61 hospital admissions for internal medicine (35 of 249 patients), and 58 for family practice (27 to 271 patients). Age (mean 47 years) and sex of patients in both groups were equivalent. The average total cost of hospitalization for each patient was greater for those randomized to the Internal Medicine Clinic: $7,193 for internal medicine patients as compared with $5,764 for family practice patients. The professional costs per hospitalization showed greater variation: $913 for Internal Medicine Clinic patients and $629 for Family Practice Clinic patients. Internal Medicine Clinic patients had a longer mean length of hospitalization (7.5 days) when compared with that of Family Practice Clinic patients (6.3 days). It can be concluded that in this clinical environment the hospitalization patterns are different for patients assigned to the Internal Medicine Clinic compared with the Family Practice Clinic: both cost and length of care for hospitalization are less for those followed by the Family Practice Clinic.