While diverticulosis of the colon is a relatively common disease, a solitary giant colonic diverticulum is rare. Although there exist some theories about the formation of the giant colonic diverticulum, none is really conclusive. The preoperative diagnosis of giant colonic diverticulum is made radiographically with findings of a large, smoothly marginated, round homogeneous radiolucency in the abdomen that is in close apposition to the colon on barium enema examination. Early surgical treatment is necessary since the complication rate is high. One case of giant colonic diverticulum is presented, the clinical, radiologic and pathologic findings are discussed, and the etiology and differential diagnosis, reviewe.