Isobaric vapor-liquid equilibria at 101.33 kPa and isothermal vapor-liquid equilibria at 308.15 K, 318.15 K, and 328.15 K for the quaternary system ethanol + acetone + benzene + hexane were measured using an inclined ebulliometer with a pumplike stirrer. The results were well correlated by the extended UNIQUAC equation with temperature-dependence binary parameters.