The results of several seismic refraction profiles on the continental shelf and slope of the eastern seaboard of Canada are now available. Gravity measurements which begin near the coast of Nova Scotia and end over the abyssal plain have also been made along two tracks perpendicular to the shelf edge. Various models for the crustal and upper mantle structure are presented. A density distribution assumed for each model resulted in a computed gravity field satisfying the observed gravity measurements. The models in agreement with all seismic data suggest that horizontal and vertical density variations occur in the upper mantle down to 100 km. The results indicate a mantle density of 3.42 g/cm3 under the continental shelf and 3.32 g/cm3 under the ocean basin.