Background : The bioavailability of a generic preparation of aceclofenac(Acer from Kyungdong Pharmaceutical Company) was evaluated in comparison with a proprietary product(Airtal from Daewoong Pharmaceutical Company). Methods : Sixteen healthy male volunteers participated in the study conducted according to a two-way crossover, open-labeled Latin square design. The bioavailability was compared using the parameters total area under the plasma concentration-time curve$(AUC_{0-{infty}})$, peak plasma concentration$(C_{max})$ and time to reach peak plasma concentration$(T_{max})$. Results : No statiscally significant difference was observed between the values of the two products in all three parameters. Moreover, the 90% confidence interval for the ratio of the logarithmic-transformed $AUC_{0-{infty}};and;C_{max}$ values of Acer over those of Airtal was found to lie between 0.94-1.03 and 0.94-1.06, respectively, being within the acceptable bioequivalence limit of 0.80-1.25. Conclusion : These findings indicate that the two preparations are comparable in the extent and rate of absorption.