Three representative group contribution activity coefficient models, UNIFAC-FV, Entropic-FV and UNIFAC-r, were evaluated and compared for the prediction of the thermodynamic factor relating to the self- and the mutual-diffusion coefficients in polymer solutions using the experimental data of 40 polymer solution systems with 438 data points. The calculated results show that the three models have similar accuracy. The average absolute deviation (AAD) is around 20 % for most systems, and the deviation is rather large for some systems. This work shows a potential problem in the calculation of a mutual-diffusion coefficient from the self-diffusion coefficient, that is, large uncertainty caused by the calculation of the thermodynamic factor with an existing activity coefficient model may affect significantly the predictive accuracy of the mutual diffusion coefficient even the self-diffusion coefficient model used is very accurate.