Liquid-liquid equilibrium data for the quaternary systems (water + 1-butanol + acetone + sodium chloride) and (water + 1-butanol + acetone + sodium acetate) were measured at 20 and 40 degreesC. The results were compared with experimental liquid-liquid equilibrium data for the ternary, salt-free systems, both from literature and determined in this work. In this way, the salt effect could be, evaluated. Ternary liquid-liquid equilibrium data for the salt-free system water + acetone + 1-butanol were also determined and found in good agreement with reported data from literature. The experimental data were correlated with the NRTL activity coefficient model. New thermodynamic interaction parameters were estimated with the Simplex method and the Maximum Likelihood principle, using binary water + 1-butanol liquid-liquid equilibrium data from literature, ternary water + acetone + 1-butanol, both from literature and determined in this work, and quaternary water + acetone + 1 -butanol + salt, determined in this work. The results are very satisfactory in accordance with root mean square deviations between experimental and calculated compositions of both equilibrium phases, that are always below 1.2%.