To clarify the prognosis of axillary and subclavian deep venous thrombosis and to determine which clinical factors influence its sequelae, we systematically reviewed the English-language literature published on this subject since 1950. Seventy-one case reports and 17 case series describing a total of 329 patients met our inclusion criteria for detailed review. There were major deficiencies in the quality, as well as quantity, of the available clinical data: few patients were enrolled at axillary and subclavian deep venous thrombosis inception, and outcome assessments were susceptible to bias and based on insensitive diagnostic tests. Posttreatment symptoms were reported in 34% of cases, pulmonary embolism in 9.4% (one half documented by lung scan or angiography), and death in 1.2% (three of four deaths due to pulmonary emboli). These complications occurred regardless of etiologic category (spontaneous, catheter related, or miscellaneous). Thrombolytic agents and surgery, in addition to anticoagulation, were often used to treat axillary and subclavian deep venous thrombosis, but there were no controlled trials to support any one approach. Until such trials are performed, therapy should be based on the anticoagulation regimens proved to be effective for deep venous thrombosis of the lower extremity. In selected patients, thrombolytic therapy and surgery may have important roles.