This study evaluated the long-term outcome of renal transplantation in type 1 (n = 25) and type 2 (n = 18) diabetic patients. Overall postoperative survival at 1 year was 69% in type 1 diabetes and 75% in type 2; at 5 years it was 62% in type 1 diabetes and 58% in type 2. Death was due mainly to cardiovascular disease (60%) and septic gangrene (20%). Outcome was examined in terms of graft function, which was poor in the majority (86%) of patients who died. Patients with fatal outcome suffered major vascular complications prior to renal transplantation and frequently had impaired graft function. Metabolic control was better in patients with good graft function (HbA1c < 6.2%) than in those with poor or no function of kidney transplant (HbA1c > 9.8%). In the absence of severe vascular complications renal transplantation may be the treatment of choice for both type 1 and type 2 diabetic patients with end-stage renal disease. Otherwise, renal transplantation is not able to improve the prognosis of patients with a history of severe vascular complications prior to renal replacement therapy.