The occurrence of an acute thrombosis of the axillary vein subsequent to effort has been recognized for forty years, but no adequate causal factor has been established. CHARACTERISTICS OF A TYPICAL CASE Following slight or more marked exertion but without direct injury to the vein, there is a progressive swelling of the arm with pain usually referred to the axilla. With the increase in edema are evidences of collateral circulation, and cyanosis is of frequent occurrence, although pallor may be present. Palpation of the axilla reveals a hard, indurated cord, sensitive to pressure. The development of these phenomena usually occurs without fever, and is succeeded by a period of rapid, or more often tardy retrogression. This summarizes the history of a typical case of "thrombose par effort," a spontaneous thrombosis following exertion. REVIEW OF THE LITERATURE The kind of effort seems as varied as the theories advanced for its method