Bicyclol(SY 801) is an anti-hepatitis drug. Oral administration of bicyclol normalizes the elevated serum transaminases (ALT, AST) by 50% in chronic viral hepatitis B and C, and also has a certain level of inhibiting HBV and HCV replication. In combination therapy of bicyclol with interferon alpha, lamivudine and adefovir dipivoxil in HBV or HCV, bicyclol may reduce YMDD mutant and side effects and increase the anti-viral efficacy.