To assess the impact of diabetes on vascular complications occurring in renal transplant recipients, we compared the incidence of vascular disease in 283 non-diabetic (ND) and 99 diabetic (D) patients who received primary cadaver renal transplants at our center between 1/1/76 and 12/31/85. The median observation time in the ND patients was 31 months, and in D patients it was 20 months. Both ND and D patients were subdivided into group A if they had preexisting clinical vascular disease and group B if they had no prior disease. The vascular complications between the ND and D patients were analyzed in 3 subsets: prevalence of vascular disease prior to renal transplantation; posttransplant recurrent vascular disease in group A; and posttransplant vascular disease, new, in group B. The results showed that, prior to renal transplantation, D patients have a higher prevalence of clinical vascular disease (33%), compared with ND patients (13%) (P = .00001). In group A, the recurrence rate of vascular disease after transplantation was also higher in D patients (67%) compared with ND patients (40%) (P = .05). In group B, the incidence of posttransplant vascular disease (new) was significantly higher in D patients (33%) compared with the ND patients (13%) (P = .002). Also, the amputation rate was significantly higher in D patients (18%) compared with ND patients (0.4%) (P = .000001). Our data suggest that morbidity from vascular disease is significantly increased in diabetic renal transplant recipients compared with nondiabetic patients. Such increased morbidity from vascular disease in the diabetic patients may also be observed in the period before renal transplantation.