A gravity survey of the UK sector of the North Sea reveals the presence of three gravity lows over the Mid North Sea High. Seismic data eliminate the possibility that these lows are due either to thicker sediments or to salt structures. Consequently, the anomalies may be related to buried granites within the Palaeozoic basement. Gravity modelling demonstrates that the amplitude and shape of the observed anomalies may be explained by buried batholith-shaped bodies with densities appropriate for granites. The tectonic influence of the buried granites may explain to some extent the continued stability of the Mid North Sea High throughout much of the development of the North Sea basins.