Summary 1. Thirteen examples of duplication of the gastrointestinal tract are reported. All 13 patients underwent successful operative treatment. 2. In all instances symptoms were present during infancy; the severity of the symptoms was dependent on the location of the duplication. 3. Preoperative diagnosis in most instancesis difficult. The treatment of choice of these congenital lesions is surgical correction. 4. Duplications of the alimentary tract in infants and children are more important pediatric problems than is generally believed, and awareness of these lesions will lead to earlier diagnosis and treatment.