Venous aneurysms are rare lesions. They may, however, be the source of pulmonary emboli and can result in death. We have recently treated several patients who had venous aneurysms of the upper extremity and jugular system. In these locations, venous aneurysms appear to have a safe natural history, although two patients required surgery after the development of symptoms. These cases are presented, with a review of venous aneurysms occurring at other sites and their cause.