Surface elevations of the ice sheet are contoured at 50-m intervals for the region of Greenland covered by SEASAT radar altimetry south of 72¿N and at 100-m intervals for a region of East Antarctica north of 72¿S. The surface elevations were obtained from computer retracking of the radar altimeter waveforms, which were recorded at 0.1-s intervals corresponding to 662-m spacings on the surface. The precision of the elevation measurements before adjustment for radial orbit errors is 1.9 m as shown by analysis of elevation differences at orbital crossover points. This precision is partly determined by radial errors of approximately 1.0 m in orbit determination and partly by noise due to ice surface irregularities. Adjustment of the radial components of the orbits to minimize the differences in elevations at crossovers over a small, relatively flat region reduces the rms difference to 0.25 m, which is indicative of the optimum precision obtainable over the ice sheets. However, the precision degrades as the slope of the surface or amplitude of the undulations increases, yielding an overall precision of ¿1.6 m. The preliminary contour maps are not corrected for slope-induced displacements. A 2-m contour map in a region of highest data density illustrates the three-dimensional characteristics of some surface undulations.