FIVE PROVED cases of lymphosarcoma of the gastrointestinal tract occurring in adult patients were treated at the Carle Hospital Clinic in the five-year period from 1947 to 1953. These cases are reviewed for the purpose of pointing out certain characteristic features of the disease. Although unrecognized findings suggestive of lymphosarcoma were present in some of the cases, in none was the correct diagnosis made before histological studies of the tissues were completed. The stomach was the site of the tumor in two cases, the appendix and ileocecal region in one, the descending colon in one, and a unique involvement of the entire colon in one. A biopsy for diagnosis was the extent of the surgery in this case. A preoperative diagnosis of carcinoma was made in each of the first four cases. The reported incidence of lymphosarcoma of the gastrointestinal tract relative to that of carcinoma varies from 1: 100