This 1993 report of the Lombardy Regional Dialysis and Transplant Registry refers to all the data collected between January 1, 1983, and December, 31, 1992, by means of individual patient questionnaires sent to all of Lombardy's 44 renal units (100% replies). The number of patients recorded by the Registry as being alive progressively increased; by the end of 1992, the number was 6,014 (655 patients per million population): 4,770 patients were on dialysis treatment (515 patients per million population, 79.3%) and 1,244 patients (140 patients per million population, 20.7%) had received a kidney graft. The acceptance rate for dialysis increased from 64 per million population in 1983 to 102 per million population in 1992; the increase in the transplant rate was much lower (from 18.7 to 21.3 per million population). The percentage of primary nephropathies in the new patients accepted for dialysis treatment were 22.0% glomerulonephritis, 13.8% interstitial nephritis, 15.2% vascular diseases, 10.1% cystic kidney, and 10.6% diabetes. The use of acetate hemodialysis declined over the 10-year period from 72.4% to 17.5%; that of bicarbonate hemodialysis increased from 8.8% to 50.1% and that of hemodiafiltration increased from 0.2% to 11.1%. The prevalence of hospital hemodialysis was stable, ranging from 55.4% to 52.2%; home hemodialysis decreased from 15.7% to 5.3%, continuous ambulatory peritoneal dialysis increased from 13.3% to 19.6%, and limited care increased from 13.7% to 22.4%. The crude death rate increased from 7.5% in 1983 to 10.5% in 1992. The survival rate (Kaplan-Meier) of all patients on dialysis was 78.8% at 2 years, 62.2% at 4 years, and 40% at 8 years; for transplanted patients, the survival and graft survival rate at 2 years was, respectively, 95% and 86%. The relative death risk of the patients on peritoneal dialysis with respect to those on hemodialysis was 1.419, as estimated by the Cox proportional hazard regression model. The main causes of deaths of patients on dialysis treatment during the year 1992 were cardiovascular diseases (47.0%) and cachexia (19.5%); in transplanted patients, they were cardiovascular diseases (36.6%) and infections (34%). Registries are not only important for planning health care but are also very useful instruments for clinical research.