LYMPHOSARCOMA of the thyroid is infrequently reported. In a twenty-two year period (1924 through 1945) 8 patients with this disease were operated upon at the Cleveland Clinic. Because of the paucity of reported cases of lymphosarcoma of the thyroid in the literature, this series will be presented here. Pool (1) in 1927 reported 2 patients with lymphosarcoma of the thyroid who died within eight months of the time of local extension. Means (2) has seen 3 cases in which lymphosarcoma appeared to arise in the thyroid gland. Hertzler (3) felt that lymphosarcomas of the thyroid were most distinctive and definitely not epithelial in origin. Graham (4) stated that many cases reported in this country as small cell carcinomas are in reality lymphosarcomas. Some of these appear to be remarkably responsive to irradiation, and some persons who have this disease may survive for many years. Anderson (5) on the other hand, warned that small cell carcinomas of the thyroid are easily mistaken for lymphosarcoma. Karsner (6) emphasized that care must be taken to distinguish lymphosarcoma from small cell carcinomas. Crotti (7) agreed that, in accordance with the more recent observations, the round cell carcinoma was to be regarded as a lymphosarcoma.