There are two anatomic varieties of carcinoma of the small intestine: adenocarcinoma and carcinoid tumor. The former is more common than the latter, but both types are rare. The histogenesis of carcinoid tumors is obscure, and their clinical course is not generally understood. Many investigators have considered them benign, yet a number of cases in which metastasis occurred have been reported. The purpose of this study is to report 11 cases of carcinoid tumors of the small intestine that have not heretofore been reported and to summarize the literature on the subject. Since metastasis was present in 3 cases, the series is divided into a malignant and a benign group. MALIGNANT LESIONS1 Case 1. —History. —A man, aged 67, had been operated on for cholelithiasis three years previous to admission. During the last year he had had persistent diarrhea with frequent, thin, watery stools. A dull, aching epigastric pain