A filter module includes a first filter stage and a second filter stage which are substantially concentrically arranged. The first filter stage and the second filter stage each include a plurality of hollow fiber membranes having a first fiber end and a second fiber end, which are embedded in a respective casting compound. The first filter stage is a filter stage for the filtration of a first medical fluid, and the second filter stage is a filter stage for the filtration of a second medical fluid. The first filter stage has unilaterally closed fiber ends, and is surrounded by a boundary element which separates the first filter stage and the second filter stage from one another. The boundary element has at least one opening which provides fluid communication between the first filter stage and the second filter stage.
