A specified group-contribution method is proposed to estimate vapor-liquid equilibria (VLE) of ordinary and associated binary polymer solutions. van der Waals (vdW) energy parameters for dispersion and polar forces for ordinary systems without hydrogen bonding (h-b; Case I) are determined. In addition, the h-b energy parameters for associated systems are employed. Two cases are, respectively, taken into account for associated systems: solvent activities by the h-b interactions are nearly independent of the temperature (Case II); and solvent activities by the h-b interactions strongly depend on the system temperature (Case III). The temperature-dependent h-b parameter is also considered. Our proposed model shows good agreements with experimental data in solvent activity estimations for ordinary and associated binary polymer solution. (C) 2003 Elsevier Science B.V. All rights reserved.