A filter medium for the filtration of oil, in particular in the oil circuit of gear mechanisms and internal combustion engines, comprises a first and a second filtration layer, the first filtration layer comprising an open filtration medium and being arranged on the second filtration layer comprising a tight filtration medium, an intermediate chamber being arranged between the first and the second filtration layer, so that the first and the second filtration layer are set apart from each other in the region of the intermediate chamber in the direction of filtration.