Methylmercury (Me-Hg) poisoning (Minamata disease: MD) is one of the most severe types of disease caused by humans to humans in Japan. The disease is a special class of food-borne methylmercury intoxication in humans as typified by the outbreak that began in 1953 in Minamata and its vicinity in Kumamoto Prefecture, Japan. There are 450 autopsy cases in Kumamoto and 30 autopsy cases in Niigata Prefecture related to MD in Japan. Two hundred and one cases in Kumamoto and 22 cases in Niigata showed pathological changes of MD. This report provides a brief research history and overview of the pathological changes of MD, and also presents representative cases of adult, infantile and fetal forms of MD among the 450 MD-related autopsy cases in Kumamoto Prefecture.