Two-dimensional gravity modelling across the Faeroe-Shetland Basin was carried out on the basis of a published regional seismic section (Stoker et al. 1993). The existing seismic interpretation of the faulted northwest margin of the basin, where the geometry and thickness of the prospective section is obscured by Tertiary basalts, required some modification to be reconciled with the gravity data and is considered a suitable target for detailed gravity modelling. The presence of the interpreted Lewisian basement high in the central area of the basin (Flett Ridge) cannot be reconciled with the gravity data. The preferred interpretation is that the ridge has a cap of pre-Cretaceous sediment about 2 km thick resting on basement. The total thickness of Tertiary sills intruded into the Cretaceous and Paleocene strata in the Flett Basin is estimated to be about 1000 m. In the example described gravity modelling has significantly improved the seismic interpretation and may especially help with understanding the structural interpretation under areas obscured by volcanics.