Although popliteal venous aneurysms are uncommon, they are also potentially fatal because they can cause a pulmonary embolism. The authors report a case of a popliteal vein aneurysm in a healthy, asymptomatic 32-year-old patient as well as a review of the literature. Popliteal venous aneurysms are a rare but treatable cause of recurrent pulmonary embolism, with their true incidence probably being underestimated. Whenever possible, we recommend early surgical repair of both symptomatic and asymptomatic popliteal venous aneurysms because they are associated with an ill-defined risk of pulmonary embolism and death if left untreated.