Description: Evaporation/condensation at the ocean surface is an important factor of energy transport between ocean and atmosphere. This latent heat flux LE is usually determined from ship observations of SST, specific humidity and windspeed using the bulk formula. This study shows how microwave soundings by the SMMR flown on NIMBUS 7 can be used to estimate LE globaly. In July 83 the data of the SMMR are strongly affected by solar heating of the instrument. Over the North Atlantic Ocean the ascending parts of the orbits give better results than the descending ones. In addition parameters derived from SMMR measurements (SST and total water vapor amount W) have to be corrected for a systematic error. Data of the descending parts have been neglected. Infrared da ta from the AVHRR have been used to correct the sea surface temperature. After the correction the monthly mean values for 1° x 1° bins show a higher accuracy (0.95 K) as ship values (1.28 K). The correction of W is based an a comparision with rawinsonde data. Several methods have been tested to determine the surface-level humidity from SST and W. A global regression gives the best results. SMMR data can only provide low accuracy windspeeds. Therefore a wind field is used, which is determined from ship observations of wind and surface pressure by an objective analysis (Bumke & Hasse 1989). Latent heat flux is estimated from these parameters for actual satellite orbits and the monthly mean of July 83 with a 1° x 1° resolution. The resulting LE-field shows the same pattern as the ship results but has more structures.