The aim of the paper was to determine the stability and the decomposition intensity of selected polycyclic aromatic hydrocarbons (fluorene, anthracene, pyrene, and chrysene) in soils that are under agricultural use. Soil was sampled from the arable layer that is representative of the Kujawy and Pomorze Provinces, which are located in the northwestern part of Poland. The soil samples were polluted with selected PAHs at an amount corresponding to 10 mg PAHs/kg. PAH-polluted soil samples were incubated for 10, 30, 60, 120, 180, and 360 days at a temperature of 20-25 °C and a fixed moisture of 50% field water capacity. High-performance liquid chromatography (HPLC) was used to determine the content of PAHs. It was found that the process of the degradation of PAHs was most intensive during the first 30 days of the experiment; however, three-ring PAHs (fluorene and anthracene) definitely decomposed faster than the four-ring ones (pyrene and chrysene). The results also confirm the significant role of soil organic matter in sorption and activation processes of PAHs.