Ischemic colitis is the most frequent form of intestinal ischemia and arises when the colon is temporarily deprived of blood supply. Diagnosis of this entity requires a high index of clinical suspicion. To achieve this, the chronology of the symptoms (abdominal pain followed by defecatory urgency and rectorrhagia) and the clinical context in which these symptoms appear (> 90% affect persons especially at risk for vascular accidents) must be taken into account. Although diagnosis requires early colonoscopy (< 48 h), this procedure should not be performed if peritonitis is present. In severe forms, other imaging techniques, such as Doppler ultrasound or abdominal computed tomography, provide information with diagnostic -and even prognostic- value. Angiography is reserved for patients in whom there is doubt about the presence of acute mesenteric ischemia. Thrombophilia should be investigated in persons aged less than 60 years old.