The analysis of some basic chemical and physical properties of drained fen peat and moorsh soil layers. The paper presents the results of measurements of some chemical properties for 14 drained fen peat-moorsh layers taken from north-east, central and east part of Poland. These areas were drained in order to use as a grassland and most of them in former time were under sub- -irrigation systems. The following basic chemical properties were analysed: organic C, total N, C:N ratio, pH and ash content. In the paper also the relationships between some basic chemical and physical properties were analysed (ash content with bulk density, particle density and porosity). Increasing of ash content caused the decreasing of some chemical properties (organic carbon and total nitrogen content) and increasing some physical properties (bulk density and particle density).