Ondansetron is a potent, highly selective 5-hydroxytryptamin $e_3$(5-H $T_3$) receptor-antagonist, for the management of nausea and vomiting induced by cytotoxic chemotherapy and radiography, and the treatment of post-operative nausea and vomiting. The purpose of the present study was to evaluate the bioequivalence of two ondansetron tablets, Zofran (Glaxo Smithcline Korea Ltd.) and Onfran (Korea United Pharmaceutical Co., Ltd.), according to the guidelines of Korea Food and Drug Administration (KFDA). Eighteen normal male volunteers, 24.39$pm$1.69 year in age and 69.00$pm$6.74kg in body weight, were divided into two groups and a randomized 2${ imes}$2 cross-over study was employed. After one tablet containing 8mg of ondansetron was orally administered, blood was taken at predetermined time intervals and the concentrations of ondansetron in plasma were determined using HPLC with UV detector. Pharmacokinetic parameters such as AVC, $C_{max}$ and $T_{max}$ were calculated and ANOVA test was utilized for the statistical analysis of the parameters. The results showed that the differences in AUC, $C_{max}$ and T max between two tablets were 5.83％, 5.75％ and －5.71％, respectively when calculated against the Zofran, tablet. The powers (1-$eta$) for AUC, $C_{max}$ and $T_{max}$ were above 90％, above 90％ and below 60％, respectively. Minimum detectable differences($Delta$) at alpha=0.1 and 1-$eta$=0.8 were less than 20％ (e.g., 12.74％ and 11.78％ for AUC and $C_{max}$ respectively). But minimum detectable differences($Delta$) at alpha=0.1 and 1-$eta$=0.8 for $T_{max}$ were more than 20％ (e.g., 34.22％). The 90％ confidence intervals were within $pm$20％ (e.g., -2.73∼14.39 and -2.16∼13.67 for AUC and $C_{max}$ respectively). But 90％ confidence intervals for $T_{max}$ were not within $pm$20％ (e.g., -28.71∼17.28). Another ANOVA test was conducted for logarithmically transformed AUC and $C_{max}$. These results showed that there are no significant difference in AUC and $C_{max}$ between the two formulations: The differences between the formulations in these log transformed parameters were all for less than 20％ (e.g., 5.83％ and 5.75％ for AUC and $C_{max}$ respectively). The 90％ confidence intervals for the log transformed data were the acceptance range of log 0.8 to log 1.25 (e.g., log 0.99∼log 1.15 and log 0.98∼log 1.15 for AUC and $C_{max}$ respectively). The major parameters, AUC and $C_{max}$, met the criteria of KFDA for bioequivalence although $T_{max}$ did not meet the criteria of KFDA for bioequivalence, indicating that Onfran tablet is bioequivalent to Zofrm1 tablet.t is bioequivalent to Zofrm1 tablet.m1 tablet.m1 tablet.m1 tablet.