To improve the solubility properties of indomethacin, a poorly water-soluble drug, some attempts were made with surfactants, such as sodium deoxycholate, sodium laurylsulfate and polysorbate-80. The enhancement effect in solubility was found to be due to the micellar solubilization and dependent on the concentration of surfactants, pH and temperature. The mechanism of interaction was suggested to be attributed to the formation of mixed micelles between the drug and solubilizers.