Between 1982 and 1989, 78 children with diarrhoea-associated haemolytic uraemic syndrome (HUS) were referred to this hospital. Most presented with abdominal pain, bloody diarrhoea and vomiting. Seven had severe gastrointestinal involvement, four of whom required resection for bowel perforation or necrosis. One also developed an oesophageal stricture, a previously unreported complication of HUS. These seven children had a high incidence of other complications including hypertension, and cerebral and pancreatic involvement. One died from severe cerebral involvement, one has a residual neurological deficit and one has residual renal impairment. Severe gastrointestinal involvement did not significantly affect the long-term outcome. Simple haematological indices helped predict severe gut involvement. Four of the 78 children had undergone appendicectomy before the diagnosis of HUS was made. The operative findings were in no case typical of primary acute appendicitis, although histological examination did confirm inflammation of the appendix in two patients. Diagnosis is difficult in early disease, but increased awareness may help prevent unnecessary appendicectomy.