Excess enthalples H-E for various kinds of binary systems at low and high pressures are well represented by the PRSV equation of state with the modified Huron-Vidal first order (MHV1) and Wong-Sandler (WS) mixing rules. The NRTL and modified UNIQUAC excess. Gibbs free energy G(E) models with linearly temperature-dependent parameters are used for the two mixing rules, introducing the parameters determined from low-pressure vapor-liquid and liquid-liquid equilibria. Good predictions are obtained for strongly non-ideal ternary systems. Simultaneous representation of vapor-liquid equilibria and H-E data is also made for four binary systems using the present equation of state/G(E) models.