Venous aneurysms are rare cause of neck masses. Among neck veins, external jugular vein aneurysms are incredibly uncommon. We, herein, report the case of a 45-year-old woman who presented with a non-tender, non-pulsatile, progressively enlarging mass in the left supraclavicular region. B-mode and Doppler ultrasound examination showed a saccular dilatation of the external jugular vein. Saccular aneurysms of the external jugular vein are uncommon, and serious complications are rarely encountered. Ultrasonography with color flow duplex imaging can allow early detection of such venous aneurysms of the neck making the other imaging methods unnecessary.