We report a case of a 67-year-old woman suffering from intermittent claudication secondary to severe popliteal stenosis due to compression by a popliteal ganglion cyst extending into the adventitia of the popliteal artery. After declining vein bypass grafting, this patient was successfully treated using ultrasound-guided aspiration of the cyst, which restored normal flow to the popliteal artery. Whilst aspiration of Baker's cysts causing claudication has been attempted before, this represents the first reported case of successful recanalization of the popliteal artery by ganglion cyst aspiration and further supports an important possible aetiology and treatment for cystic adventitial disease.