The vapor-liquid equilibria for the ternary systems methanol-diethyl ketone-methyl Isobutyl ketone and methanol-methyl ethyl ketone-methyl Isobutyl ketone were determined at 760 mmHg by using a Dvorak and Boubllk recirculation still. The data were correlated by means of the Wilson and Redlich-Kister equations and by an equation based on the separation factor. Direct correlation of the ternary data without considering binary data was found very efficient. The prediction of the binary and ternary data by the UNIFAC method was good. Bolling points of the ternary mixtures were predicted by an empirical correlation within a mean error of ±1.0%.