Duplications of the alimentary tract may be defined as those cystic and tubular structures found in relation to normal bowel whose walls resemble intestine and consist of smooth muscle with alimentary tract mucosa. Synonyms for duplication include enterocystoma, enterogenous cyst, enteric cyst, giant diverticulum, ileum duplex, gastroenteric cyst, gastrogenous cyst, and reduplication of the intestine. "Atypical" and "ectopic" Meckel's diverticula are usually duplications. Single reports and reports of small numbers of cases in the literature suggest that duplications occur infrequently. This report concerns 25 cases in which one or more alimentary tract duplications were present. were Negro and 22 were white. There were 12 male and 13 female patients. Duplications were discovered or confirmed at surgery in 19 cases. Duplications were discovered at necropsy in six patients. In three instances (Table 1) it was small and had been asymptomatic. In the remaining three patients of this group, the unrecognized duplication