Only 2 comprehensive surgical series, published in 1977 and 1983, have evaluated clinicopathologic features of the ascending aorta. Retrospective review of medical records and microscopic slides was performed on 513 consecutive patients with surgical resection of ascending aortic tissue (1985 to 1999). Patients were 2 to 89 years old (mean 59 y), and 303 (59%) were men. Aneurysm or dissection was the indication for surgery in 479. Aortic valves were also excised in 360. Systemic hypertension was present in 279, inherited connective tissue disease (ICTD) in 67, arteritis in 33, and acquired connective tissue disease in 16. Microscopy showed cystic medial degeneration (CMD) in 209, aortic dissection (AD) in 109 (with CMD in 56), normal media in 90, aortitis in 57 (with CMD in 14), and other findings in 48. The most significant, independent risk factor of CMD and AD was ICTD (confidence interval=7.61 and 2.26, respectively). Systemic hypertension was more common in patients with AD than without (P=0.0202). Normal media was the most common histologic finding associated with bicuspid aortic valve (P<0.0001). Among 57 patients with aortitis (giant cell in 39), ages ranged from 16 to 85 years (mean 64 y), and 42 (74%) were women; only 8 had Takayasu arteritis, and 11 had temporal or systemic arteritis. In surgically resected ascending aorta, the 3 most common histologic findings were CMD, AD, and normal media. ICTD, systemic hypertension, and bicuspid aortic valve were common comorbid findings. Giant cell aortitis occured predominantly in women, usually without systemic disease.