Of the 309 patients operated on for revascularization of lower extremities 29 (9.4%) had a conventional contrast arteriography that failed to opacify at least one vessel that was found to be patent by color Doppler imaging plus surgical exploration. The indication for vascular imaging was rest pain in 12 patients, claudication in 7, nonhealing ulcers in 3, and gangrene in 3; 4 patients had more than one indication. In 20 (69%) of 29 patients infrapopliteal runoff vessels were the cause for misdiagnosis. In all patients with failed arteriography a total occlusion proximal to the misidentified vessel was present. As a common finding, peak systolic velocities were less than 0.5 m/second in misdiagnosed suprapopliteal arteries and less than 0.25 m/second in infrapopliteal arteries.