Lovastatin, one of the potent cholesterol-lowering agents, is an inactive lactone prodrug which is metabolized to its active open acid, lovastatin acid (LVA). Bioequivalence study of two lovastatin preparations, the test drug (Mevacor^ⓡ: Chungwae Pharmaceutical Co., Ltd.) and the reference drug (Lovaload^ⓡ: Chong Kun Dang Pharmaceutical Co., Ltd.), was conducted according to the guidelines of Korea Food and Drug Administration (KFDA). Fourteen healthy male volunteers, 23.9±3.9 years old and 67.6±8.0 ㎏ of body weight in average, were divided randomly into two groups and administered the drug orally at the dose of 160 ㎎ as lovastatin in a 2×2 crossover study. Plasma concentrations of lovastatin acid were analysed by HPLC method for 12 hr after administration. The extent of bioavailability was obtained from the plasma concentration-time profiles of total lovastatin acid after alkaline hydrolysis of the plasma samples. By alkaline hydrolysis, trace amounts of unmetabolized lovastatin were converted to lovastatin acid. The AUC_(0-12hr) was calculated by the linear trapezoidal rule method. The C_(max) and T_(max) were compiled directly from the plasma drug concentration-time data. Student`s t-test indicated no significant differences between the formulations in these parameters. Analysis of variance (ANOVA) revealed that there were no differences in AUC, C_(max), and T_(max) between the formulations. The apparent differences between the formulations were far less than 20% (e.g., 7.07, 5.77 and 1.18% for AUC, C_(max), and T_(max), respectively). Minimum detectable differences(%) between the formulations at α=0.05 and 1-β=0.8 were less than 20% (e.g., 17.2, 15.1, and 15.9% for AUC, Cmax, and Tmax, respectively). The 90% confidence intervals for these parameters were also within ±20% (e.g., -5.20∼19.3, -5.00∼16.5, and -10.2∼12.5% for AUC, C_(max), and T_(max), respectively). These results satisfied the bioequivalence criteria of KFDA guidelines, indicating that the two formulations of lovastatin were bioequivalent.