This work reports the experimental results of the densities and refractive indices of the ternary system methyl acetate + methanol + 2-butanol and the corresponding binary systems methyl acetate + a-butanol and methanol + a-butanol at 298.15 K and atmospheric pressure. A vibrating tube digital densimeter and a refractometer of synthetic sapphire prism (sodium D wavelength) were used, the whole mole fraction range being covered. Excess molar volumes and changes of refractive index on mixing were determined from experimental data, and different estimation equations that are dependent of binary contributions were analyzed. Variable-degree polynomials have been fitted to the results. Values of densities and refractive indices are evaluated and compared by different methods. Excess partial molar volumes and those corresponding to the infinite dilution condition are also calculated.