In January 2017, the new realization of the International Terrestrial Reference Frame (ITRF) – ITRF2014, was released. Besides the higher accuracy and consistency of the new frame, an entirely new element – the post seismic deformation - was included. Moreover, the definition of the fundamental points has also been changed. All changes related to the new reference frame haveconsequences in the precise positioning using GNSS observations. In this paper, on the basis of results and analysis obtained from Bernese 5.2 software package, the most important changes, related to GNSS data processing are presented. Our analysis confirmedthat the differences between ITRF2008 and ITRF2014 are minor. However, changing GNSS antenna calibrations from IGb08 to IGS14 causes changes of stations coordinates up to several millimeters, especially for the vertical component. This effect is mainly due to the introduction of new or updated absolute antenna calibrations. Such changes of coordinates have also impact on the realizationof the European Terrestrial Reference Frame (ETRF).