The effect upon patient satisfaction of a reorganization of a traditional medical clinic into a group practice model was examined in a controlled trial in which both patients and physicians were randomized. The group practice model, unlike the traditional clinic, provided decentralized registration, 5 days/week clinic coverage, and night/weekend phone coverage. Residents worked in small groups with an attending physician, a nurse practitioner, and a receptionist. This reorganization resulted in a substantial decrease in charges and utilization for patients in the experimental group. A panel of 302 patients was interviewed prior to the reorganization and 1 year later. Patients in the experimental groups perceived improvements in access to their physicians as well as decreases in clinic waiting time and decreases in the lag time between requesting and obtaining an appointment. General health perceptions and other satisfaction measures were unchanged. The authors conclude that a group practice organization can result in decreased patient charges without substantially altering patient satisfaction.