EN
In this paper the result of the many year's studies on groundwater flow in Middle Biebrza Basin and in it's vicinity was presentend, especially in the aspect of dependence in the differentiation of groundwater flow from the morfo-geological conditions. Basing on its, and considering hydrogeological conditions inside Basin and in the area arrounding it, author separated six regions for calculation the value of inflow the groundwater into the Basin. Calculations were done using Darcy's formula for hydrogeological cross-sections which were interpreted as a representative for each region. The coefficient of groundwater inflow which was calculated for Middle Biebrza Basin is changed from 0.009 mm per day to 0.656 mm per day (the average 0.092 mm per day). The results of the investigations and calculations were presented on maps, draws, and tables.