DUPLICATIONS are spherical or elongated hollow structures which (1) possess a coat of smooth muscle, (2) are lined by a mucous membrane similar to some part of the alimentary canal, and (3) are intimately attached to some portion of the alimentary tube. They may appear at any level from the base of the tongue to the anus and are more commonly found in relation to the small intestine than to any other part of the gastrointestinal tract.1 Of those found in the small intestine, the duodenum is least often involved. Because of the uncommon occurrence of duplication cysts in the duodenum and the special problems encountered in its management when in this location, the following case is being reported. Report of Case This 52-year-old Negro woman (260763 HH) had a one-year history of anorectal disease beginning as an abscess in the left ischiorectal fossa. In August 1965, the abscess