The authors examined the effect of after-hours telephone access to physicians and physician access to computerized medical records on hospitalizations and emergency room (ER) visits in an inner-city, adult, general medicine clinic. Patients were randomly assigned to a control (C) and two study groups (S1 and S2). Patients in study groups S1 and S2 had after-hours telephone access to physicians. Computerized medical records were accessible to physicians only for callers in study group S2. During the initial 18 months of study, only 7.6% of eligible patients called the after-hours service, a rate of 6 calls/1,000 patients/month (200 calls/1,849 patients/18 months). Repeated promotion of the service was subsequently undertaken, and 19.4% of the patients used the service during the final 12 months of study, a rate of 24.1 calls/1,000 patients/month (467 calls/1,616 patients/12 months). There were no significant differences in hospitalizations or ER visits among the control and two study groups.