Renal failure is an important cause of morbidity and mortality in diabetic patients, who account for up to 25 per cent of new patients entering renal replacement therapy. Between 1980 and 1989, 651 patients with renal failure were treated at King's College Hospital, of whom 177 (27 per cent) had diabetes. Of these 177 patients 148 had diabetic nephropathy (65 non-insulin-dependent), while the rest had other renal diseases. Of the non-insulin-dependent diabetics, 45 per cent (29 of 65) were Asian or Afro-Caribbean compared to only 12 per cent (10/83) of the insulin-dependent diabetics. Ninety-two patients (62 per cent) have received a renal transplant with actuarial patient survival of 82 per cent at 1 year and 61 per cent at 4 years. Both patient and graft survival have been improved by the introduction of cyclosporin A. Continuous ambulatory peritoneal dialysis is the main form of dialysis and has allowed increasing numbers of patients to be dialysed, especially older individuals with non-insulin-dependent diabetes. Rehabilitation is best in those with functioning transplants: 21 patients (19 with functioning grafts) have survived for longer than 5 years. Diabetic complications before and after renal replacement therapy are described. Cardiovascular disease is especially common and may limit the success of renal replacement therapy.