We describe a case of a 44 year-old man with a subcutaneous swelling in the left popliteal fossa. The patient complained pain posteriorly to the left knee since several months and presented with a saccular aneurysm of the left popliteal vein (PVA) with reflux clearly evidenced at duplex ultrasound scan (DUS), but in absence of thrombus inside and without clinical signs of embolism. The patient was treated surgically by aneurysmectomy with lateral venorrhaphy according to Aldridge technique and a duplex ultrasound scan after six months revealed a complete patency of the left popliteal vein. According to literature evidences and our center experience, the surgical treatment of the popliteal vein aneurysm represents the gold standard in order to prevent the possible complications like development of thrombus inside the aneurysmatic vein and the consequent embolic risk and it is recommended in all case of a symptomatic saccular type of whatever diameter, and in fusiform type >20 mm, with or without thrombus.