BACKGROUND/AIMS: Chronic hepatocellular damage is closely associated with hepatic fibrosis and fatal complication in most liver diseases. The aim of this study is to compare the efficacy and safety of biphenyl dimethyl dicarboxylate (DDB) and ursodeoxycholic acid (UDCA) in patients with abnormal ALT. METHODS: One-hundred thirty-five patients with elevated ALT were randomized to receive either 750 mg/day of DDB or 300 mg/day of UDCA for 24 weeks in 4 referral hospitals. Ninety-three (69%) patients had non-alcoholic steatohepatitits, 27 (20%) had alcoholic hepatitis, and 15 (11%) had chronic hepatitis. The primary end point was the rate of ALT normalization at week 24. The secondary endpoints were changes in AST, liver stiffness, and the incidence of adverse events. RESULTS: A total of 101 patients completed 24 weeks of therapy. ALT normalization at week 24 was observed in 44 (80.0%) patients in DDB group and 16 (34.8%) in UDCA group (p<0.001). Higher mean reduction of ALT levels from baseline to 24 weeks was seen in DDB group compared with UDCA group (-70.0% vs. -35.9%, p<0.001). Normalization of AST level (p=0.53) and change in the liver stiffness (p=0.703) were not significantly different between the two groups. Severe adverse drug reaction occurred in 1 patient in DDB group but the subject continued therapy during the study period. CONCLUSIONS: DDB was not inferior to UDCA for normalizing ALT level. Furthermore it was safe and well tolerated by patients with abnormal ALT.