Mefenamic acid has been widely used clinically as an anti-inflammatory analgesic. It has poor solubility in water (41 ㎍/㎖) and there is the difficulty of dissolution in the mefenamic acid capsules. A study was made to investigate the effect of various surfactants on the dissolution of mefenamic acid capsules. The surfactants used were sodium lauryl sulfate (SLS), Pluronic F-68, F-77, and F-127. Mefenamic acid capsule containing surfactant showed significantly improved dissolution characteristics. The dissolution rate was fast in the order of SLS > F-77 > F-68 > F-127 in mefenamic acid capsules containing 0.2 w/w % surfactant. SLS was selected for further study on the bioavailability in rabbits. The area under the plasma concentration-time curve (AUC_(0-24)) of mefenamic acid capsule containing SLS was higher than one of mefenamic acid capsule not containing surfactant.