The authors observed 25 children at the age of from 2 mos to 14 years with the different forms of gastric and intestinal duplication. Cystic forms of duplication (16 cases) were manifested mainly by the symptoms of obstruction of the alimentary canal, diverticular duplication (3) was complicated by profuse bleeding, tubular duplication (6) was more often revealed in the rectum (4). Correct diagnosis before the operation was established in 5 patients. Choice of a method for operation is individual. The results of treatment are favourable.