An analysis of the gravity field in the Western and Eastern Carpathian junction area is based on local isostasy and forward density modelling. For the first time the lithosphere/asthenosphere boundary was taken into account for density modelling of long-wavelength gravity anomalies in this region. The gravity effects of the main geological structures within the lithosphere were estimated. To give a better view of the present lithosphere structure in this region, density cross sections were calculated along the Profile KP-X. The results demonstrate a slab-like structure under the mountain range. The slope of the underthrusted lower European Platform is very steep. Modelled slab dips from about 60° to 80°. Density modelling shows that the southern margin of the European basement bends down to the soutwest into the Carpathian subduction system. The East Slovak Basin is characterized by thinning of the crust and lithosphere. The extension process is accompained by the existence of lower crustal high-density mass.