Background Adult moyamoya disease is rare in the United States, and patients mostly present with cerebral ischemia. However, clinical and neurodiagnostic correlates of ischemia are not well known in this population. We sought to characterize the clinical and radiographic features of moyamoya disease in a large urban center in the United States, with a focus on angiographic and neuroimaging patterns of ischemia. Methods and Results We retrospectively reviewed charts of consecutive adult moyamoya disease patients evaluated at 2 centers in Houston, Texas from January 2002 to December 2011. We reviewed all available cerebral angiograms and neuroimaging studies to evaluate the Suzuki grades, presence of intracranial hemorrhage or ischemia, infarct patterns, and vascular territory distribution. Our analysis was mainly descriptive. We identified 31 adults with moyamoya disease who met our inclusion criteria. The female‐to‐male ratio was 2.4:1. The majority of patients were white, followed by Hispanic, black, and Asian. Most presented with ischemia (61%), followed by headaches, and intracranial hemorrhage. Of the 22 patients with available neuroimaging, 72.7% had ischemic findings, with the vast majority having a watershed pattern (81.3%). Conclusions We observed a high burden of ischemia, mostly watershed pattern on neuroimaging in our adult moyamoya disease patients. Long‐term monitoring of adult moyamoya disease patients in the United States would be useful to better understand the natural history of this condition.