Nitrogen, phosphorus and potassium balance in the organic and conventional crop production systems are presented in the paper. The research was conducted on a special field experiment established in 1994 at the Experimental Station in Osiny (Lublin province, Poland) on grey brown podzolic soil. In this experiment different crop production systems (organic, integrated and conventional) are compared. Organic and conventional systems are characterized by different crop rotations and crop production technologies. In the organic system (crop rotation: potato – spring barley – red clover with grass grown two years – winter wheat + catch crop) neither mineral fertilization nor pesticides were applied. The conventional system (winter rape – winter wheat – spring barley) was conducted as an intensive crop production technology. The results include the years between 1996 and 2002. The OECD method was used in this research. Balance elements were determined with the help of real data that included the rate of mineral fertilizers, NPK content in compost, seeds and seed-potatoes. Crop yields and real NPK concentrations in them were the basis for determining the outputs of nutrients. In the organic system nitrogen and phosphorus balance was slightly negative, whereas in the case of potassium a significantly negative balance on the level of 131 kg K ha-1 was noted. In the conventional system there was a surplus for all nutrients – the largest for nitrogen (72 kg N ha-1) and the smallest for phosporus (14 kg P ha-1). Rape was the crop that charged the nutrient balance in the highest degree in this system. An average annual surplus for this crop exceeded 80 kg N ha-1.