 This study is a 24-week multicenter, randomized, double-blind control trial with ursodeoxycholic acid UDCA in patients with chronic hepatitis C in Japan. The primary objectives of this study are to verify the superiority of efficacy of UDCA 600 or 900mgday to that of 150mgday and the safety of UDCA treatment. The primary endpoint was percent changes of serum alanine aminotransferaseALT levels at 24-week of administration compared to pre-administration levels and secondary endpoints, serum aspartate aminotransferaseAST and gamma-glutamyltranspeptidasegamma-GTP levels. Further, changes of bile acid composition and HCV-RNA levels at 24-week of administration were examined. 