To elucidate the molecular mechanism involved in methylmercury-induced cerebellar disorder, we performed DNA microarray analysis of the cerebellum of methylmercury-treated mice. The expression levels of 21 genes were elevated 2-fold or higher in response to methylmercury, including many genes encoding proteins involved in inflammatory reactions associated with chemokines. The expression levels of 11 genes were reduced by half or more in response to methylmercury.