A filter device (10) for filtration of fluids, in particular for the dialysis of blood. The filter device (10) comprises a housing (12) having a first end (14) and a second end (16) and defining a fluid chamber (18) extending between the first end (14) and the second end (16). The filter device (10) further comprises a first lid (20) provided at the first end (14) of the housing (12) and comprising a first fluid port (22), a first compartment (24), a second compartment (26) and a first internal separating wall (28) separating the first compartment (24) from the second compartment (26). The filter device (10) further comprises a second lid (30) provided at the second end (16) of the housing (12) and comprising a second fluid port (32), a third fluid port (33), a third compartment (34), a fourth compartment (36) and a second internal separating wall (38) separating the third compartment (34) from the fourth compartment (36). The filter device (10) further comprises a plurality of hollow fibers (40) arranged within the housing (12), wherein each of the plurality of hollow fibers (40) comprises a semi-permeable membrane and defines a fluid channel extending longitudinally through an interior of the respective hollow fiber (40). The filter device (10) further comprises a first sealing means (42) which separates the fluid chamber (18) from the first and the second compartment (24, 26), the first sealing means (42) having a first longitudinal end facing away from the second lid (30). The filter device (10) further comprises a second sealing means (46) which separates the fluid chamber (18) from the third and the fourth compartment (34, 36), the second sealing means (46) having a second longitudinal end facing away from the first lid (20). Still further, the filter device (10) comprises a fourth fluid port (50) and a fifth fluid port (52) both provided at the fluid chamber (18) and located between the first longitudinal end of the first sealing means (42) and the second lon
