Two personal cases of ischaemic gangrene of the colon required emergency surgery. The two cases provide the basis for a discussion of the aetiopathogenetic, anatomo-pathological and clinical aspects of this pathology. Stress is laid on the fact that ischaemic colitis in its various anatomo-pathological signs is not easy to diagnose and needs early treatment of conservative or emergency surgery type depending on its anatomo-pathological expression.