A 33 year old woman presented with abdominal pain and bloody diarrhea. A subtotal colectomy was performed. Following surgery the haemolytic uraemic syndrome unmasked. Such surgical forms of haemolytic uraemic syndrome are rare. They demonstrate that the diagnosis is difficult at the initial abdominal period before renal insufficiency and anemia develop. Review of the literature confirms the severe nature of haemolytic uraemic syndrome associated lesions. Haemolytic uraemic syndrome and pseudomembranous colitis with capillary thrombosis would be two forms of a unique affection, i.e. thrombotic microangiopathy.