BACKGROUND The rs112735431 polymorphism of the RNF213, a susceptibility variant for moyamoya disease (MMD), may be associated with non-MMD intracranial artery steno-occlusive disease of non-MMD type (non-MMD ICAD) in Asian. We investigated whether the rs112735431 polymorphism of the RNF213 affect the development of non-MMD ICAD in Koreans compared to MMD and control group. METHODS We included 31 patients with non-MMD ICAD, 25 patients with MMD, and 100 participants as control group. The rs112735431 polymorphism of the RNF213 was evaluated by polymerase chain reaction amplification of target and detection by restriction fragment length polymorphism analysis. Clinical phenotype was compared between patients with and without the rs112735431 polymorphism in non-MMD ICAD and MMD. RESULTS The rs112735431 polymorphism of the RNF213 was significantly associated with non-MMD ICAD (p=0.001; odds ratio, 14.3; 95% confidence interval, 2.80-73.2) and MMD (p<0.0001; odds ratio, 126.0; 95% confidence interval, 24.2-656.0). The rate of hypertension was more frequent in MMD with the rs112735431 polymorphism than MMD without polymorphism (p=0.010). CONCLUSIONS The rs112735431 polymorphism of the RNF213 is highly associated not only with MMD but also with non-MMD ICAD in Koreans. Also, our study suggests that the rs112735431 polymorphism of the RNF213 may be linked to the hypertension in MMD. Further studies are needed to clarify the relationship between the rs112735431 polymorphism of the RNF213 and hypertension in patients with MMD.