Biphenyl dimethyl dicarboxylate (DDB) has been used for the treatment of chronic viral hepatitis B and drug-induced hepatitis through the inhibition of lipid peroxidation and c ovalent binding of drug metabolites to lipids of microsomes. The bioequivalence of two DDB products was evaluated according to the guidelines of KFDA. The test product was Hepaphil soft capsule(R) made by KMS Pharm. Co. Containing 3 mg DDB and the reference product was Nissel tablet(R) made by Taerim Pharm. Co. Containing 25 mg DDB. Twenty healthy male subjects, 25.4(22~30) years old and 66.7(54~77)kg, were divided into two groups and a randomized $2{ imes}2$ cross-over study was employed. After two tablets or two capsules were orally administered, blood was taken at predetermined time intervals and the concentration of DDB in plasma was determined using a validated HPLC method with UV detector. Two pharmacokinetic parameters, $AUC_t$ and $C_{max}$, were calculated and analyzed statistically for the evaluation of bioequivalence of the two products. Analysis of variance was carried out using logarithmically transformed parameter values. The 90% confidence intervals of $AUC_t$ and $C_{max}$ were log 0.91~log1.00 and log 1.05~log 1.15, respectively. These values were within the acceptable bioequivalence intervals of log 0.8 to log 1.25. Thus, the criteria of the KFDA guidelines for the bioequivalence was satisfied, indicating that Hepaphil soft capsule is bioequivalent to Nissel tablet.