Moyamoya disease (MIM 252350) is characterized by stenosis or occlusion of the terminal portions of the bilateral internal carotid arteries and by abnormal vascular networks at the base of the brain. There is a high incidence of moyamoya disease in Asia, especially in Japan. Multifactorial inheritance is estimated with lambda(s)>40. Previous linkage studies have indicated that susceptibility loci for the disease are located on chromosomes 3p, 6q, and 17q. In the present study, we searched for loci linked to the disease in 12 Japanese families using 428 microsatellite markers and found significant evidence for linkage to 8q23 [maximum LOD score (MLS) of 3.6] and suggestive evidence for linkage to 12p12 (MLS=2.3). The present study revealed a novel locus for moyamoya disease.