Twenty seven cases of haemolytic-uraemic syndrome (HUS) were admitted to the Royal Aberdeen Children's Hospital between 1978 and 1989. All cases were from the defined childhood population of the Grampian region of Northeast of Scotland. Thirteen cases were admitted during the 2-year period 1987-1988 (Group 1). Of the 13 cases, 9 (Group 1 a) were admitted within the 11-month period between August 1987 and June 1988, and were from a small area (7 miles radius) within and around the City of Aberdeen. Their mean age was 7.1 years. Twelve cases of HUS were admitted between 1978 and 1986 and 2 cases were admitted in 1989 (total 14 cases; Group 2). Mean age was 3.0 years with no geographical clustering. The average annual incidence for group 2 was 1.25 per 100,000 children 0-16 years old.