Balance velocities for the Greenland ice sheet have been calculated from a new digital elevation model, accumulation rates compilation and anexisting ice thickness grid, using a fully two-dimensional finite difference scheme. The pattern of velocities over the ice sheet is presentedand compared with velocities derived from synthetic aperture radar interferometry for part of northern Greenland and a limited number ofGPS data. This comparison indicated that the balance velocity scheme and boundary conditions used here provide a remarkably goodrepresantation of the dynamics of the ice sheet inland from the margins. It is suggested, therefore, that these balance velocity data couldprovide a valuable method of constraining a numerical ice sheet model. The balance velocities were compared with the diagnostic velocityfield calculated from several different configurations of a numerical ice sheet model. The general pattern of flow agrees well. the detail,however, is quite different. For example, the large (greater than 300 km) ice stream in the north east is not generated by the numerical modeland much of the detailed flow pattern is completely lost due to the limited model resolution and limitations in the model physics.