A broad variety of thermodynamic models were used for the prediction of vapor-liquid equilibria (VLE) of ternary polymer-mixed solvent systems. Two fundamentally different types of models were used. The first group consists of purely predictive models based on the group-contribution concept and on the Hansen solubility parameters. These are the activity coefficient models Entropic-FV/UNIFAC, UNIFAC FV. Flory-Huggins/Hansen, GC-Flory and the equation of state GCLF. The second group consists of the molecular models SAFT equation of state, Entropic-FV/UNIQUAC, Flory-Huggins and the Panayiotou-Vera equations of state. For these models, binary interaction parameters were estimated from experimental vapor-liquid equilibria (VLE) data for binary systems, and the behavior of the ternary systems was then predicted using these parameters. The models were tested on the basis of all existing literature data, and the accuracy of the predictions were found to vary, more depending on the system than on the model used. In general, the models provide similar results, and the differences between the models fall within the uncertainty of the experimental data. The accuracy of the molecular models is at the same level as the group-contribution models. This is surprising, but the comparison is based on limited experimental, some of which may be associated with uncertainties. (C) 2004 Elsevier B.V. All rights reserved.