Two patients with tuberous sclerosis had multiple semispherical polyps in the large intestine, predominantly in the rectosigmoid colon. These were hamartomas with an excess of smooth muscle fibers in the stroma. In addition, the 21-year-old man had multiple tiny protrusions in the esophagus and oral fibroepithelial polyps. In the 31-year-old woman, who had pulmonary lymphangiomyomatosis with positive estrogen and progesterone receptors, hamartomatous gastric polyps, colonic leiomyoma, and adenomatous rectal polyps were also identified. Our findings suggest that gastrointestinal polyposis may be one of the phenotypes of tuberous sclerosis complex, possibly linking this disease with other hereditary polyposis syndromes.