The phenomenon of lake tides is investigated for the subglacial Lake Vostok, East Antarctica. A model computation of equilibrium lake tides leads to a maximum lake level variation of about 18mm. To verify the hypothesis of really existing lake tides data from two different observational techniques are analysed. The re-evaluation of old tidal gravity data from Vostok Station as well as satellite synthetic aperture radar interferometry (InSAR) reveal specific signals which are explained as lake tides. The results of gravimetric tidal observations at Vostok Station from 1969 [Schneider, 1971; Schneider and Simon, 1974] show systematic deviations from the expected solid earth tide signal which correspond to a vertical tidal displacement of 12 and 2 mm amplitude for the waves K1 and M2, respectively. The InSAR data show the areal pattern of a vertical motion at the southern lake tip which is analogous to the grounding zone of ice shelves.