The impact of the Earth tides on the coordinate changes of EUPOS®-RIGA and EPN stations has been studied. The EPN stations were selected at the sites located more or less close to the Struve triangulation arc. EUPOS and EPN reference stations have been used and Bernese v.5.0 software in kinematic mode was applied. Only the Moon and the Sun tide effect was analyzed in practical calculations neglecting the influence of major planets. The standard data sets were taken from IGS data base – ionosphere and troposphere parameters, satellite orbits, satellite clock corrections, as well as the Earth rotation parameters. Earth tidal vertical displacements at GNSS stations have been obtained by modifying the routine of Bernese GPS Software computing tidal station displacements in accordance with the latest IERS Conventions. Consequently, the tidal corrections of station displacements caused by lunar and solar gravitational attraction have not been taken into account in computing process. The positioning accuracy was discovered as well.