abstract: In the years 1994-2003 the research on the impact of precipitation on the erosion of mineral nitrogen compounds from agriculturally used soils was conducted in the Olsztyn lakeland. It was stated that amount of nitrogen outflow with drainage water was highly dependent on pre-cipitation amounts (humidity of a year), soil compaction and land use. Higher amounts of precipitation in wet and normal years caused a significant increase in N outflow with drainage systems. Depending on precipitation amounts, the outflow of N from 1 ha of agriculturally used catchment via drainage network was 0.38 kg in a very dry year, 2.62 kg in a normal year and 3.57 kg in a wet one. Nitrogen outflow during wet years was 2-13 times higher.