This is the first report of a venous aneurysm detected by radionuclide venography. Aneurysms of the popliteal vein are very rare. Described here is a case of a saccular popliteal venous aneurysm that presented as dyspnea secondary to pulmonary embolism. In this case, there was recurrent PE despite anticoagulant therapy. Almost all such aneurysms are associated with PE, about half of which are recurrent. This report demonstrates another useful aspect of obtaining a simultaneous radionuclide venogram when performing a perfusion lung scan with Tc-99m MAA.