Dilated colon is provoked by obstructing lesions, toxic megacolon or colonic pseudoobstruction. The obstructing lesions of the colon are colonic volvulus, inflammatory bowel disease with stenosis or colonic cancer. Toxic megacolon is more often caused by I.B.D. and rarely by infectious diseases. Etiological diagnosis is possible after clinical and radiological evaluation. Colonoscopy is always indicated, except in toxic megacolon. Balloon dilatation of strictures, palliative treatment of colonic carcinoma by Laser procedures, reduction of colonic volvulus and aspiration of colonic pseudoobstruction are the principal indications of therapeutic colonoscopy in the non surgical treatment of dilated colon.