The prognosis of hemolytic uremic syndrome was studied in 37 children hospitalized between January 1980 and January 1985. 75% of affected children were less than 3 years of age. Twenty-two (60%) presented with anuria or oliguria (mean duration of anuria: 10.7 days). In this last group, severe extrarenal manifestations occurred: 12 cases of neurological involvement (6 involving hypervolemia), gastrointestinal involvement in 5 cases, including a case of ileal necrosis; pancreatic involvement in another. Three children died during the first month of the disease (overall death-rate: 8%). Thirty-two children were followed with a mean 24 months follow-up (6 months to 60 months). Six (19%) presented with sequellae, of which 3 were severe: one severe arterial hypertension and two with chronic renal failure of which one terminal with severe neurologic sequellae. The existence of extrarenal manifestations implies a poor prognosis. Among the 22 children with anuria or oliguria, 8 had no extra-renal manifestations. All of these recovered. Three of 11 children with one extrarenal manifestation had an unfavorable outcome. The course was unfavorable in the 3 cases with multiple extrarenal involvement.