The crustal structure in the interior of Greenland is largely unknown because of its remote location below the up to 3.4-km-thick ice sheet. We present a model of the crustal velocity structure in central-eastern Greenland based on simultaneous inversion of P and S receiver functions for data acquired at 23 broadband stations between the coast and the center of the ice sheet. The area is believed to mainly include Precambrian basement and includes a part covered by Tertiary volcanic rocks and some sedimentary basins. Our results show a westward deepening Moho from less than 20 km at the coast to 50 km below central Greenland. Crustal S wave velocities are generally 3.75 km/s through the whole crust which may be relatively small for Precambrian areas, and V _p /V _s is generally around 1.73, although slightly higher in central Greenland. In the coastal area we observe anomalously low velocities at the top of the crust. In the volcanic area south of Scoresbysund Fjord this layer has very high V _p /V _s (>2), which indicates a high mafic content and the presence of water-filled cracks in the basaltic material. In the north, outside the volcanic area, V _p /V _s is normal and the low-velocity layer probably is instead related to the presence of sedimentary basins. At stations in the center of our study area we find low V _s and high V _p /V _s in the lower crust. Based on the Moho topography, our results do not support Airy type isostasy as explanation of the high topography in eastern Greenland.