Isolated noninfectious ascending aortitis (I-NIAA) is increasingly diagnosed at histopathologic review after resection of an ascending aortic aneurysm. PubMed was searched using the term aortitis; publications addressing the issue were reviewed, and reference lists of selected articles were also reviewed. Eleven major studies investigated the causes of an ascending aortic aneurysm or dissection requiring surgical repair: the prevalence of noninfectious aortitis ranged from 2% to 12%. Among 4 studies of lesions limited to the ascending aorta, 47% to 81% of cases with noninfectious aortitis were I-NIAA, more frequent than Takayasu arteritis or giant cell arteritis. Because of its subclinical nature and the lack of "syndromal signs" as in Takayasu arteritis or giant cell arteritis, I-NIAA is difficult to diagnose before complications occur, such as an aortic aneurysm or dissection. Therefore, surgical specimens of dissected aortic tissue should always be submitted for pathologic review. Diagnostic certainty requires the combination of a standardized histopathologic and clinical investigation. This review summarizes the current knowledge on I-NIAA, followed by a suggested approach to diagnosis, management, and follow-up. An illustrative case of an uncommon presentation is also presented. More follow-up studies on I-NIAA are needed, and diagnosis and follow-up of I-NIAA may benefit from the development of diagnostic biomarkers.