摘要Gastrointestinal duplication is an uncommon congenital abnormality in two-thirds of cases manifesting before the age of 2 years. Ileal duplication is common while colonic duplication, either cystic or tubular, is a rather unusual clinical entity that remains asymptomatic and undiagnosed in most cases. Mostly occurring in pediatric patients,colonic duplication is encountered in adults only in a few cases. This study reports two cases of colonic duplication in adults. Both cases presented with rectal bleeding on admission. The study was focused on clinical, imaging,histological, and therapeutical aspects of the presenting cases. Gastrografin enema established the diagnosis in both cases. The cystic structure and the adjacent part of the colon were excised en-block. The study implies that colonic duplication, though uncommon, should be included in the differential diagnosis of rectal bleeding.