Experimental tie-line results are reported for acetic acid + benzene + triethylamine and acetic acid + chloroform + triethylamine at 25 degrees C. A three-parameter Wilson equation, proposed by Novak et al. for binary partially miscible mixtures, is extended to reproduce liquid-liquid equilibria for many ternary mixtures. The proposed form of the modified Wilson equation is not identical to that used by Novak et al. for ternary mixtures, although both forms include three additional ternary parameters. Calculated results show a good performance comparable to that of the modified Hiranuma-Wilson equation, which contains four parameters for binary partially miscible mixtures.