High-resolution CT angiogram (CTA) has replaced traditional diagnostic angiography as the main preoperative imaging modality for vascular surgery patients. Although the use of CTA is increasing for arterial imaging, it has not been used routinely for vein mapping. The goal of this study was to evaluate the accuracy of CTA for venous anatomy and compare it to a standard venous duplex ultrasound (DUS). When the vein was used for bypass, the quality and size of the vein were evaluated in the operating room. As part of a preoperative workup before lower extremity revascularization, 16 patients underwent a CTA followed by a DUS. Although the CTA provided useful arterial anatomy, the greater saphenous vein (GSV) was also evaluated. In total, 22 GSV were evaluated in 11 patients. The vein diameter was measured by CTA at four locations: saphenofemoral junction, midthigh, knee joint, and midcalf region. Duplication or other anomalies were also noted, when present. These measurements were taken by an interventional radiologist independently and before the DUS. Routine vein mapping with diameter measurements were then performed with DUS in a vascular laboratory by registered vascular technicians. Measurements for each limb were then compared between CTA and DUS using linear regression (mean ± SD). There was no statistical difference in the diameter of the GSV when measured using a CT or a DUS at the standard points of measurements. Furthermore, the operative findings confirmed the CTA to be very accurate. There were four duplications in the GSV which were all seen on the CTA, whereas only two of these were identified by DUS. There was one vein found to be sclerotic and unusable by DUS that was not identified by CTA. CTA is as accurate as DUS for evaluation of superficial venous anatomy in the lower extremities. CTA can provide global anatomy and can be used as a one-stop imaging modality for both arterial and venous anatomy. However, sclerosis is not detected by CTA.