The major clinical and pathologic features of 100 cases of syphilitic aortitis, autopsied from 1950 to 1960, are reviewed. Decreasing incidence, changing patterns of lesions, and reasons for the frequent failure to diagnose syphilitic heart disease are considered. Aortic insufficiency or aneurysm of the thoracic aorta, or both, accompanied by a history of syphilis or reactive serology are required to establish a definitive diagnosis. Syphilis still remains a real threat, and, until it is eradicated, it will continue to cause clinical and subclinical cardiovascular disease.