We observed 73 patients with the hemolytic uremic syndrome (HUS) in 9 years (1980-1988), comprising 34% of patients with acute renal failure treated over the same period. There were 53 boys and 20 girls; 59% were below the age of 2 years and 33% between 2 and 5 years. Acute, usually severe dysentery, responding poorly to various antibiotics, was the prodromal illness in 80%, whereas 12% had watery diarrhea. Most patients had severe renal involvement with anuria in 56% and oliguria in 30%. A polymorphonuclear leukocytosis was present in 85% of cases, but had no correlation with the highest levels of blood urea. Coagulation abnormalities suggesting consumption coagulopathy were found in 24 of 30 cases. The results of stool culture showed Shigella species in 7 cases and nontyphoidal Salmonella in 9. Escherichia coli were isolated in 11 cases, but were not further characterized. Renal biopsy showed total or patchy cortical necrosis in 20 of 50 cases. The patients were managed with supportive care, including transfusion of fresh blood or plasma and dialysis as required. The mortality was 60%, being chiefly related to the duration of renal failure and presence of renal cortical necrosis, whereas persistent dysentery and infections were complicating factors. The presence of convulsions and coagulation defects had no relation to the outcome. Our observations indicate that HUS in children in northern India is mostly related to dysentery, likely to be shigellosis, and is usually associated with severe renal damage and a high death rate.