Coronary artery disease (CAD) has been shown in previous uncontrolled studies to be a limiting factor to long-term survival in patients undergoing cardiac transplantation and who were taking conventional immunosuppressive agents. To study the development of CAD after cardiac transplantation in patients taking the newer immunosuppressive agent cyclosporine, we prospectively performed yearly coronary arteriography on all eligible transplantation patients (first year, 57 patients; second year, 30 patients; third year, 14 patients). The prevalence of CAD by life table analysis was 18% at 1 year, 27% at 2 years, and 44% at 3 years. The occurrence of two or more major rejection episodes was associated (p less than .005) with the development of CAD. In two patients who died of CAD, coronary artery histology revealed subintimal inflammatory cellular infiltration in some lesions. These data demonstrate that the prevalence of CAD rises progressively over time and immunologic factors may be important in its development.