For the azeotropic ternary systems which contain water, acetic acid, and either ethyl acetate, or N-propyl acetate, or N-butyl acetate as the entrainer, the binodal curves and the tie-lines are, respectively, determined using the titration method and the cross-section method at 25℃ and 40℃. With the UNIQUAC model, these experimental equilibrium data are correlated with good accuracy. The UNIQUAC parameters for the binary pair of water and acetic acid are almost entrainer-independent. However those model parameters appear to be influenced by the temperature of phase separation to a considerable extent.