Ischaemic colitis in the haemolytic-uraemic syndrome led to surgical complications of colonic necrosis or haemorrhage in 4 out of 62 patients treated during an 8-year period. Perforation occurred in the 2nd week of the illness and regular cultures of peritoneal dialysate fluid gave early warning of impending perforation. Persistent haemorrhage occurred late in the illness, and required surgical excision of the affected bowel