In 1982-3, 35 children from the West Midlands developed the haemolytic-uraemic syndrome. This was a higher incidence than expected and included an epidemic localised to the Wolverhampton area in July 1983 which comprised 11 cases in two weeks. Twenty three children were treated with dialysis, of whom three died. Six patients developed chronic renal failure, four of them from Wolverhampton. Extrarenal manifestations included neurological sequelae in four, two of whom also developed insulin dependent diabetes mellitus and chronic renal failure. Cardiomyopathy occurred in one child, who also had chronic renal failure. The outcome of these 35 patients was not predictable from prognostic criteria derived from previous experience in Britain. This, together with the high prevalence of extrarenal disease and the geographical localisation of the 1983 outbreak, suggested an aetiological agent new to the region. Faeces from 10 patients were examined for verotoxin producing Escherichia coli, and positive strains of serotype O157.H7 were found in three patients during the Wolverhampton outbreak.