Mutual solubility data of the binary systems (methanol + alpha-pinene or beta-pinene) at temperatures ranging from 288.15 K close to upper critical solution temperatures, and ternary liquid-liquid equilibria and tie-lines of the mixtures (methanol + ethanol + alpha-pinene or beta-pinene) at temperatures 288.15 K, 298.15 K, and 308.15 K have been measured. The experimental binary and ternary liquid-liquid equilibrium data have been correlated by the original, extended, and modified UNIQUAC models. Good agreement between the experimental and correlated values was obtained using the extended and modified UNIQUAC models. The temperature dependence of the binary and ternary liquid-liquid phase equilibria (methanol + alpha-pinene or beta-pinene) mixtures with ethanol was demonstrated experimentally and represented by the extended and modified UNIQUAC models.