Passive microwave satellite data provide extremely important information about the climate and surface conditions in the often cloudy high latitude regions of the Earth. Available since 1978, multichannel passive microwave data have great potential for long term climate monitoring. In order to ensure consistent data sets for such long term monitoring, the relations between the microwave brightness temperatures from similar sensors on successive satellite platforms must be understood. In this study the 19,22. and 37GHz channels of the Defense Meteorological Satellite Program (DMSP) F8 and F11 Special Sensor Microwave Imager (SSMI) instruments are compared. While the analysis shows that the two data sets are highly correlated with correlation coefficients greater than 0·98. the consistency between the two data sets can be improved by applying small corrections in the order of I deg K. Two sets of regression coefficients are provided for adjusting the F11 data to the F8 baseline.