BACKGROUND: A daily injection of glycyrrhizin (Stronger Neo-Minophagen C (SNMC) containing 40 mg glycyrrhizin in a 20 mL ampoule) lowers alanine aminotransferase (ALT) levels in patients with chronic viral hepatitis. METHODS: The therapeutic effects of intermittent administration of SNMC three times a week for 12 weeks were evaluated and compared between two doses (40 and 100 mL) in a randomized clinical trial. RESULTS: Overall, the therapeutic response was better in the 53 patients allocated 100 mL than the 59 who were allocated to have 40 mL SNMC (P = 0.0243). At the completion of SNMC treatment, ALT levels decreased more extensively in the patients on 100 mL than those on 40 mL SNMC (-29 vs-50% in comparison with the baseline value, P = 0.0002). Minor side-effects occurred in both the patients on 100 mL (20%) and those on 40 mL (12%), but they did not require any therapies. CONCLUSIONS: Intermittent SNMC would be efficient in suppressing ALT levels in patients with chronic viral hepatitis in a dose-dependent manner. Taken along with infrequent and very mild side-effects, long-term intermittent SNMC would benefit patients with chronic hepatitis by maintaining their quality of life with easier compliance. Copyright 2002 Blackwell Publishing Asia Pty Ltd