A case of multiple giant sigmoid diverticula is described in which a barium enema revealed two giant diverticula communicating with the sigmoid lumen. Both diverticula were located on the mesenteric border of the sigmoid colon, and histologic examination showed mucosal and serosal layers with no evidence of smooth muscle. The pathogenesis, pathology, radiological manifestations and differential diagnosis of this rare condition are discussed. © 1991 The Royal College of Radiologists. All rights reserved.