BACKGROUND Bovine aortic arch (BA) occurs in approximately 15-35% of the US population and is regarded as a clinically insignificant, normal variant. The aim of this study was to assess the prevalence of types I (type I bovine arch [T1BA], common origin of innominate and/or left common carotid artery) and II (type II bovine arch [T2BA], left common carotid originating from innominate) bovine arch in patients with and without thoracic aortic pathology. METHODS We retrospectively reviewed all serial computed tomography images (n = 817) performed at our institution over 4 months to determine the overall prevalence of BA. Thoracic aorta and/or arch vessels were visualized, with images read by certified radiologists. A separate analysis compared a series of 156 consecutive patients with thoracic pathology (dissection or aneurysm ≥ 4.0 cm), from a 25-month period, with 757 control patients without pathology from the original sample. Statistical analysis included a chi-squared contingency table. RESULTS Analysis revealed a bovine arch prevalence of 31.1% (n = 254), including 14.9% T1BA and 16.2% T2BA. Patients with thoracic aortopathy (n = 156) had aortic dissection (n = 26) or aneurysm (n = 130). These patients were older and had an increased prevalence of hypertension, hyperlipidemia, and aortic calcification. In addition, there was increased prevalence of T2BA in the pathology group (23.7%) compared with controls (15.9%; P = 0.03). T1BA was not significantly different between groups (11.5% vs. 14.9%; P = 0.59). When thoracic disease was stratified by pathology type, T2BA occurred more frequently in patients with thoracic aortic aneurysm (24.6% vs. 15.9%; P = 0.04). BA trended upward, in patients with thoracic aortic dissection (42.3% vs. 30.8%; P = 0.28). CONCLUSIONS Our analyses revealed a prevalence of bovine arch of 31% in our patient population. BA occurred more frequently in patients with thoracic aortopathy than controls. Therefore, patients with BA may be associated with higher levels of thoracic aortic pathology and may benefit from increased clinical vigilance.