ABSTRACT
Radon 222Rn in deep borehole water of Pojezierze Mazurskie region has been quantitative determined. The measurement were performed using the alpha liquid scintillation counting method. The water samples were examined from three voivodships: Elbląg, Olsztyn and Suwałki. In some cases the concentrations of 222Rn in investigated water samples exceed 11 Bq/1.