Abstract. Satellite data are used to study water balance in large river basins in the East European Plain. For this purpose, the accuracy of estimates of snow water equivalent (SWE) based on microwave remote sensing data was evaluated through the comparison of these data with SWE measurements in open and forested areas. The errors of the SWE estimates, evaluated as their relative root-mean-square deviations from the measured values, are maximal in the Northern Dvina basin (53%); for the Oka and Don river basins, the errors are 35 and 33%, respectively. The main problems of remote sensing for northern river basins occur due to the thick canopy and the high snowpack, whose height exceeds the penetration depth. For the southern regions and midland river basins, a priority problem is due to the presence of liquid water in the snowpack during thaws.