The introduction of cyclosporine into widespread clinical use has resulted in improved patient survival following cardiac transplantation. As a result of increased numbers of cardiac transplants, the inherent nephrotoxicity of cyclosporine, and prolonged patient survival, cardiac transplant recipients commonly present with renal dysfunction. In the subgroup who ultimately develop end-stage renal disease (ESRD), therapeutic options include renal transplantation. However, the clinical course associated with this treatment modality is unknown. From 1980 to 1993, 430 cardiac transplants were performed with cyclosporine-based immunosuppression at the Standard University Medical Center. Fourteen (3.3%) patients developed ESRD, requiring chronic dialysis or renal transplantation. The cause of ESRD was cyclosporine nephropathy (13/14; 93%) and glomerulonephritis (1/14; 7%). The average time interval to the development of ESRD was 82 +/- 42 months. Nine patients underwent renal transplantation. During the period of followup (38 +/- 27 months; range 6-89 months) after renal transplantation, cardiac function remained stable. There were no episodes of primary nonfunction of the renal allograft. Patient and renal allograft survival was 89% at both 1 and 3 years after renal transplant. Average serum creatinine was 1.3 +/- 0.6 mg/dl at 1 year and 1.6 +/- 0.8 mg/dl at 3 years post-transplant. The incidence of infectious complications was not statistically different when compared to that of the heart transplant controls and that of a group of cadaveric renal transplant controls (n = 20). Surprisingly, the incidence of renal allograft rejection in the heart transplant patients was 10-fold less than that of the renal transplant controls (0.006 +/- 0.02/patient-year vs. 0.062 +/- 0.05/patient-year; p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)