Deep venous thrombosis (DVT) of the upper extremity has recently been recognized as being more common than previously reported (probably because of the increasingly frequent use of subclavian venous access). A retrospective review of patients in whom subclavian or axillary DVT had developed in the past 6 years (1980 to 1986) was conducted at the Akron General Medical Center. The major cause identified was related to subclavian venous catheterization, which accounted for 39% of all instances of subclavian and axillary DVT. Our results are correlated with a review of the literature. In our review of studies in which subclavian venous catheterizations were prospectively examined with use of objective means of diagnosis, we found that 28% of all subclavian catheterizations had venous thrombosis develop, often subclinically. This is not an innocuous disease, as suggested in the past; in our series 12% of upper-extremity DVT had pulmonary embolization (PE). In reviewing the recent literature, we found an average 12.4% incidence of PE, which often occurs during anticoagulation treatment. Diagnostic modalities are discussed and treatment regimens are reviewed along with an extensive literature review.