To develop a aceclofenac soft capsule, four preparations with various solubilizers were prepared and their dissolution test was carried out. Among four preparations tested, a preparation with ethanolamine was selected as a formula of aceclofenac soft capsule (Clanza $S^{TM}$), since it showed the fastεst dissolution rate. Bioequivalence of aceclofenac tablet, $Airtal^{TM}$ (Dae-Woong Pharmaceutical Co., Ltd.) and aceclofenac soft capsule, Clanza $S^{TM}$ (Korea United Pharmaceutical Co., Ltd.) was evaluated according to the guideline of KA Fourteen normal male volunteers (age 20 - 25 years old) were divided into two groups and a randomized $2{ imes}2$ cross-over study was employed. After oral administration of one tablet or capsule containing 100 mg of aceclofenac, blood was taken at predetermined time intervals and the concentration of aceclofenac in plasma was determined with an HPLC method under UV detector The pharmacokinetic parameters ($C_{max}$ and $AUC_t$) were calculated and ANOVA was utilized for the statistical analysis of parameters using logarithmetically transformed $AUC_t$, $C_{max}$ and $T_{max}$. The results showed that the differences in $AUC_t$, $C_{max}$ and $T_{max}$ between Aral tablet and Clanza soft capsule were 2.89%, 0.18% and 43.0%, respectively. There were no sequence effects between two formulations in these parameters. The 90% confidence intervals using logarithmically transformed data were within the acceptance range of log(0.8) to log(15) (e.g. log(0.81) -log(1.23) ad log(0.89) -log(1.4)) fo $AUC_t$ and $C_{max}$, respectively. Thus, the criteria of the KFDA guidelines for the equivalence was satisfied, indicating that Clanza $S^{TM}$ soft capsule is bioequivalent to$Airtal^{TM}$ tablet.