The most frequently used conduit for infrainguinal or coronary artery bypass is the saphenous vein, and this report describes the ultrasonic evaluation of anatomic variations in over 1400 limbs. The thigh portion of the greater saphenous vein consisted of a single venous conduit in 67% of the limbs, a complete double system in 8%, a branching double system in 18% and a closed loop double system in 7%. In 92% of the cases, the vein was in medial position, with the remaining 8% positioned laterally. In the calf, a single vein was observed in 65% of the limbs with the remainder demonstrating a double venous system. The vein was positioned anteriorly in 85% of the limbs. The remaining 15% were positioned posteriorly, with 7% of these being a single dominant vein. Proper knowledge of saphenous vein anatomy is vital to the surgeon preparing to use this vein as a bypass conduit and can aid in its preoperative assessment.