Phlebectasia of the internal jugular vein (IJV) is a rare entity with only 25 cases having been reported. Clinically this condition presents with enlargement with a Valsalva maneuver and decrease at rest. Venography, anteriography, and ultrasound have previously been used to diagnose this unusual cause of neck mass. We present a case in which CT confirmed the clinical diagnosis and in which there was an incomplete ipsilateral duplication of the IJV. This is only the second case reported of IJV phlebectasia and duplication.