For the Sako-Wu-Prausnitz (SWP) cubic equation of state, parameters were determined for 10 polymers [low-density polyethylene, poly(E-caprolactone), poly(epichlorohydrin), poly(methyl methacrylate), poly(o-methylstyrene), polypropylene, poly(isobutylene), polystyrene, poly(vinyl acetate), and poly(vinyl chloride)] using literature PVT data ranging from the ambient conditions up to 470 K and 200 MPa. The correlated results of relative volume agreed with average deviations of 0.06% and were better than those of the original SWP equation (Sako et al. J. Appl. Polym. Sci. 1989,38,1839-1858). When the SWP equation is combined with the G(E) mixing rule and the ASOG-FV group contribution method, the solvent activities for polymer solutions composed of 4 polymers and 13 solvents (benzene, toluene, cyclohexane, acetone, butyl acetate, etc.) could be predicted. The prediction accuracy was somewhat better than that of PRASOGFV although the accuracy of the PVT calculation for polymers did not almost influence the prediction accuracy of the vapor-liquid equilibria for binary solutions at normal pressure.