Giant cell arteritis and Takayasu arteritis are large-vessel vasculitides that share multiple common features but also have significant differences in epidemiology, demographics, clinical presentation, evaluation, and treatment. Giant cell arteritis is more common in elderly patients of Caucasian descent versus Takayasu arteritis, which is more prevalent in younger patients of Asian descent. Although traditionally age has been the main criterion for differentiating the 2 etiologies, modifications in the diagnostic criteria have recognized the overlap between the 2 conditions. In this monograph, we review the diagnostic criteria for both conditions and describe the epidemiology, pathogenesis, histology, evaluation, and management for large-vessel vasculitis in ophthalmology. Additionally, we describe ocular imaging techniques that may be utilized by ophthalmologists to identify manifestations of large-vessel vasculiti- des in patients. Lastly, we compare and contrast the key clinical, laboratory, and pathologic features that might help ophthalmologists to differentiate the 2 entities.