Twenty three cases of acute ischaemia of the left side of the colon were seen between 1968 and 1978. The physiopathology is similar to that of acute ischaemia of the limbs and two major factors must be borne in mind : underlying arterial disease and a low systemic flow rate. Severe surgical forms may be associated with suggestive abdominal symptoms and signs (diffuse or localised peritonitis, febrile obstruction, abscess in the left flank) or there may be only a septicaemia, unexplained fever or diarrhoea. The diagnosis is based upon hydrop aque enema which shows characteristic appearances and is rarely a source of error. Only early diagnosis makes it possible to reduce the mortality below 50% in severe forms.