Intracranial atherosclerotic occlusive disease is an important and possibly the most common cause of stroke worldwide. Asian, Black and certain Hispanic populations have a high risk of harboring intracranial occlusive disease. In this chapter we review the epidemiology of intracranial occlusive disease by primarily focusing on studies from China, Japan, Korea, and other Asian countries. In addition, we compare and contrast the information from Asian countries with that from North America and related regions. Finally, we explore hypotheses concerning the origin of race-ethnic differences in the distribution of extracranial and intracranial atherosclerotic disease.