A three-dimensional geophysical model of the crust and upper mantle for Fennoscandia and adjacent regions is presented. Seismic results, gravity field and heat-flow data were used for the construction of the model. The layers, which were allocated from seismic data, and distribution of P-wave velocities in these layers served as a basis of the initial seismic model. Empirical equations of interrelation between velocity, heat generation and density were used for transforming the seismic model to thermal and density models. The influence of pressure and temperature on physical properties was investigated and taken into account. Statistical parameters of the interrelation between velocity, heat generation and density were used when solving the inverse problems for geothermal and gravity data. A brief description of the mathematical principles of integrated interpretation is also given. As a result, 3-D models of distribution of heat generation, temperature and density in the crust and upper mantle were obtained. These data are represented in horizontal and vertical cross sections outlining physical parameters for various depth levels. Finally, regional geological data are correlated with the obtained density variations in the crust.