An ASOG-based equation of state called PRASOG (Peng-Robinson ASOG) has been developed to predict vapor-liquid equilibria in non-polymer and polymer solutions. It makes use of the zero-pressure G(E) mixing rule consistent with the second virial coefficient condition for calculating the mixture parameters in Peng-Robinson EOS and predicts the G(E) using ASOG method. The first object of this paper is to predict low-pressure vapor-liquid equilibria (VLE) using PRASOG for 37 binary systems containing alcohols, hydrocarbons, ketones, esters, ethers, aromatic compounds and water. The PRASOG model has been then used to predict high-pressure VLE for ammonia-containing systems. In order to apply PRASOG to polymer solutions, PRASOG-FV has been proposed by calculating G(E) from ASOG-FV and VLE in polyisobutylene solutions have been then predicted.