We examined whether promoter region polymorphism in the tumor necrosis factor-alpha (TNFalpha) gene at position -308 affects the odds of cerebral infarction (CI). We genotyped 366 CI patients and 610 healthy controls for the same polymorphism. A significant decrease was found for the TNFalpha A allele in CI patients compared with controls (P=0.003). Our finding suggests that TNFalpha promoter region polymorphism is responsible for susceptibility to CI in Koreans.