Vapor-liquid-liquid equilibrium (VLLE) properties were measured with a static apparatus for mixtures of water + methyl acetate, water + methyl propionate, water + methyl acetate + methanol, and water + methyl propionate + methanol at temperatures ranging from 313.24 to 348.15 K. Both ternary systems exhibit type I liquid-liquid equilibrium (LLE) behavior. By checking with the Othmer-Tobias equation, the experimental tie-line data of these two ternary systems appeared to be consistent. The binary VLLE data were correlated satisfactorily with the UNIQUAC model for water + methyl acetate and water + methyl propionate. While the UNIQUAC model with the parameters determined from the phase equilibrium data of the constituent binaries overestimated the two-liquid-phase regions of the ternary systems, the representation of the binodal loci was substantially improved as the six parameters of the UNIQUAC model were determined simultaneously front the ternary VLLE data.