In this study the recharge by precipitation of the upper Narew catchment was evaluated. Data from the MARS-STAT database and from the ground net of the rain gages belonging to the Institute of Meteorology and Water Management (IMGW) were acquired for the period 1978–2002. Analysis has indicated average 5% underestimation of the mean annual precipitation estimated with the MARS- -STAT data in comparison to the IMGW data. Evaluation of monthly data brought significantly bigger differences. Presented results indicate need of precise MARS-STAT data verifi cation before this data source could be applied in hydrological modeling.