Cholecystocolic fistula is a rare cause of diarrhoea, and the diagnosis may be significantly delayed. Air in the biliary tree on imaging should raise suspicion, and barium enema or endoscopic retrograde cholangiopancreatography will be diagnostic. Cholestyramine should provide effective symptomatic relief until definitive treatment is arranged. We report on two patients with cholecystocolic fistula presenting with severe diarrhoea. They were treated successfully by endoscopic retrograde cholangiopancreatography.