Venous aneurysms may remain undetected for years due to their obscure and non-specific clinical picture. Two cases of primary saphenofemoral junction aneurysm are described, and their vague clinical picture is highlighted. The importance of increased alertness and suspicion is noted, because of the gravity of the possible complications of an undetected venous aneurysm, namely rupture of the aneurysm and/or recurrent pulmonary embolism.