From January 1968 to December 1984, 312 infants and children with hemolytic uremic syndrome were admitted to our unit; 8 patients died (2.5%) during the acute phase; 118 children were followed as outpatients at yearly intervals for at least 10 years (mean follow-up 13 years, range 10-19.8 years). Four evolution patterns at the end of the follow-up were defined: group 1, complete recovery, 74 (62.7%); group 2, proteinuria with/without hypertension, 21 (17.7%); group 3, reduced creatinine clearance, often in conjunction with proteinuria and hypertension, 19 (16.1%); group 4, end-stage renal failure, 4 (3.4%). We investigated the association between several variables of the acute stage and the long-term evolution. Most non-anuric patients recovered completely (92.5%), while 38.4% of those with 1-10 days and 69.2% of those with 11 or more days of anuria had chronic renal sequelae. Similar results were found when analyzing the requirement for peritoneal dialysis. Of the patients with proteinuria at the 1-year control, 86% had renal abnormalities at the end of the follow-up. In our experience, although the final outcome was not predictable in every instance, the severity of acute renal failure-as determined by the days of anuria- and the presence of proteinuria 1 year after the acute phase were the most useful prognostic indicators.