Comparisons between the SEASAT radar altimeter inferred estimates of significant waveheight (SWH) and wind speed with buoy measurements for near overflights are presented. Details of the 'calibration' of SEASAT's measurement of &sgr;0(0¿) against those made by the GEOS-3 radar altimeter are presented. The 'onboard' estimate of SWH is shown to be biased high by 0.5 m for SWH>2 m. Comparison of buoy measurements of SWH with altimeter waveform data processed by using the Fedor algorithm for 51 cases show a mean difference of 0.07 m with a standard deviation of 0.29 m over the range of 0.5--5 m SWH. The SEASAT inferred estimates of &sgr;0(0¿) are biased highly by 1.6 dB relative to GEOS-3 data. For 87 corrected comparisons with buoy measurements of wind speed, the mean difference is -0.25 m/s, and the standard deviation of the difference is 1.6 m/s over the range of 1--10 m/s wind speed. The numbers are very similar to GEOS-3 data comparisons and thus provide a second corroboration of the waveheight and wind speed measurement capability of a short pulse spaceborne radar altimeter.