The poor water solubility of rebamipide was enhanced by the mixed micelles of transglycosylated stevia (Stevia-G) and trimethylammonium chloride with varying carbon chain length (C(n)TAC, n = 14, 16, and 18). Fluorometry, isothermal titration calorimetry (ITC) and dynamic light scattering techniques examined the aggregation properties of Stevia-G and C(n)TAC. Synergism was found between Stevia-G and C(n)TAC using the approaches of Clint and Rubingh. The negative interaction parameter (average beta(m) = -4.17, -5.47, and -7.07) and excess free energy (average Delta G degrees(ex) = -2.47, -3.06, and -3.88 kJ mol(-1)) increased with increasing chain length of C(n)TAG. The negative B-1 values by the Maeda approach suggested that chain-chain interactions contribute to the formation of a mixed micelle. The solubilization of rebamipide in the mixed micelle was evaluated in the term of the molar solubilization ratio (MSR) and partition coefficient (K-m). The K-m from the Stevia-G/C(16)TAC system was highest at a low mole fraction of C(n)TAC (0.2-0.6). In conclusion, the solubilization of rebamipide was more favorable between Stevia-G and C(16)TAC, although the stability of the mixed micelle was enhanced by an increase in hydrophobicity of the longer chain lengths used in C(n)TAC.