OBJECTIVE: To identify clinical characteristics of diabetic end-stage renal disease patients that place individual transplant candidates at high risk for arterial morbidity and mortality after transplantation. RESEARCH DESIGN AND METHODS: We studied the course of 101 sequential renal allograft recipients with insulin-dependent diabetes mellitus, transplanted between 10 November 1980 and 1 April 1986. Arterial disorders were tabulated from medical records and interviews with individual patients, their families, and their private physicians. Documentation of discrete arterial events included recorded physical examinations, radiographic studies, laboratory data, electrocardiograms, peripheral vascular flow studies, and operative reports. The prevalence of preoperative arterial disease was compared with the occurrence of new arterial events after kidney transplantation. RESULTS: Within a mean follow-up period of 47 mo, a 30% absolute mortality rate was observed. Of these deaths, 57% resulted from arterial disorders. Clinical manifestations of arterial disease were recognized in 41% of recipients before transplantation, and 78% of these patients suffered new vascular events after transplantation. Of the entire sample, 57% developed at least one new complication of arterial disease after transplantation, whereas only 34% had no vascular diagnosis before or after transplantation. Cerebral, coronary, and peripheral arterial complications after transplantation occurred in 14, 28, and 36% of the patients, respectively. The corresponding incidences of stroke, myocardial infarction, and amputation were 12, 14, and 25%. Pretransplant coronary artery disease predisposed to new coronary events after transplantation, but only peripheral arterial complications occurred more often after transplantation compared with the preoperative period. The probability of arterial complications or death correlated with patient age at first transplant and duration of diabetes but not with sex or smoking history. CONCLUSIONS: Intrinsic arterial disease in diabetic renal allograft recipients contributes heavily to the long-term morbidity and mortality after transplantation and poses the major threat to survival. Diabetic transplant candidates greater than 35 yr of age or with clinical evidence of arterial disease should undergo an extensive vascular assessment, including stress thallium myocardial imaging and/or coronary arteriography. Such recipients should receive careful preoperative counseling about their excess risk for subsequent arterial disorders.