With the launch of the Tropical Rainfall Measuring Mission (TRMM) satellite in Dec. 1997 and the upcoming planned launch of the Aqua satellite in December 2001, we have taken the opportunity to modify and improve our Special Sensor Microwave/Imager (SSM/I) algorithm for the TRMM Microwave Imager (TMI) and Aqua Advanced Microwave Scanning Radiometer (AMSR) microwave instruments. The Version 5 operational TMI product, released in late 1999, is similar to the standard SSM/I algorithm; we made slight modifications to account for the SSM/I vs. TMI differences and improvements in the rain/no-rain classification procedure. The algorithm deficiencies, such as overestimation in convective regimes, are understood fairly well, so we have re-calibrated the algorithm using the TRMM Precipitation Radar (PR) to reduce these biases. We also have added recent advances in the classification of convective vs. stratiform rainfall to the algorithm. The respective Version 6 TMI and pre-launch AMSR algorithms had expected delivery dates in summer 2001 as of this writing. Following those deliveries, the next planned advances to the algorithm are the incorporation of numerical weather prediction model parameters, such as moisture fields, which should be helpful to rainfall estimation.