The paper presents a method and results of verification of rheological models usefulness for prognosis of changes of beech wood samples deformation in time exceeding the test time t. Analysis of variability of approximation errors of the averaging deformation course as the function of time was applied. For analysed models the minimum test time tmin was determined which permitted, with an adopted error of approximation, to predict changes of deformation in time tn, where tn > t > tmin. There was prepared a ranking of the usefulness of the models. It was found that the usefulness of a specific model for the prediction of creep was dependent on stabilisation of its parameters values as the function of time.