This paper reports the effects on a community hospital's emergency room utilization that were brought about by the development of a primary care group practice. The practice, which has replaced the hospital's traditionally structured outpatient clinics, employs full-time, salaried physicians and provides evening office hours and 24-hour coverage. The primary care group appears to have effected a substantial reduction in pediatric emergency room use. To a lesser extent, utilization by former clinic users among the adult atients was also reduced. These reductions, however, created only modest impact in the context of the hospital's total emergency room use, owed in part to the relatively small size of the patient population who formerly had depended upon the hospital for primary care.