An assessment is made of the significant wave height and wind speed measurements obtained by the Geosat radar altimeter. In comparison with buoy data, it is found that Geosat underestimated the significant wave height by 13% throughout the range of measurements. An attempt to compare the wave measurements made by Seasat and Geosat reveals problems with both data sets. For the Geosat wind speed measurements, it is found that the smoothed-Brown algorithm, usually employed to convert backscattered power to wind speed, does not give good results in comparison with buoy measurements. A simple linear relationship between backscattered power and wind speed is derived, which is in close agreement with the algorithm recently proposed by Witter and Chelton for wind speeds above 3 m s-1. The implications of these results for deriving wind and wave climatologies from altimeter data are discussed. ¿American Geophysical Union 1992