Objective: Computed tomographic angiography (CTA) has the potential to detect unsuspected extravascular pathology in patients with vascular disease. The purpose of this study was to determine the prevalence of unexpected findings, additional associated costs, and alterations in treatment in vascular patients undergoing CTA. Methods: During a recent 15-month period, 350 subjects (207 men, 143 women; mean age of 66 ± 14 years) underwent CTA for evaluation of aortic aneurysms (43%), lower extremity occlusive disease (33%), renal artery disease (17%), or aortic graft infection (7%). Unexpected CTA findings were categorized as incidental, clinically important but probably benign, or possibly serious. Medical records were reviewed to determine the outcome of additional testing and to identify alterations in treatment plans. Results: Of the 163 subjects (47%) with positive findings, 95 (27%) were categorized as incidental, 27 (8%) as probably benign, and 41 (12%) as potentially serious. Additional tests were required in 57 subjects (15%) to confirm these results. Seventeen (5%) of the 350 original subjects were ultimately considered to have life-threatening pathology found on CTA, but 11 of these were lost to follow-up. Significant alterations in treatment plan occurred in the six patients with life-threatening pathology and in one other patient with benign disease. Conclusions: These data suggest that unexpected CTA findings are common in vascular patients. Although few prove to be serious, treatment delays associated with evaluation of benign lesions are modest. Of major concern, one fourth of patients with potentially serious lesions did not undergo further evaluation in this study. Vascular surgeons need to ensure adequate follow-up for their patients with potentially serious extravascular lesions.