This study elucidated the effect of taurine on fatty liver in simple obesity. Taurine was orally administered to 10 children with fatty liver. During taurine administration, the CT numbers of the liver, which were low in the beginning, increased. Serum ALT levels were improved, especially in those children whose weight was well controlled. Even in those who failed in weight control, serum ALT levels were slightly recovered. Ratios of glycine/taurine-conjugated bile acids were decreased. Thus, taurine was effective in treating fatty liver of children with simple obesity regardless of the success/failure of weight control. Taurine administration is considered to be helpful as an adjuvant therapy for fatty liver.