Clostridium difficile causes a broad spectrum of enteric diseases in humans, ranging from mild antibiotic-associated diarrhoea to more severe pseudomembranous colitis. The authors report four cases of life-threatening pseudomembranous colitis with haemodynamic changes. Infection due to Clostridium difficile should be kept in mind whenever a patient undergoing antibiotic therapy develops a symptomatology of an acute abdomen.