The BALTEX regional reassimilation project uses meteorological data assimilation for quantifying the climatic energy and water cycles over the catchment basin of the Baltic Sea during the course of one annual cycle, Sep. 1999-Oct. 2000. This report presents the data assimilation system used, the available products, and a sample of preliminary results. The latter demonstrate that the system is capable of simulating the essential features of the energy and water cycles of the Baltic drainage basin. We find this encouraging, because the model has not been tuned to reproduce these cycles, but mainly to predict the atmospheric state.