The invention relates to a blood filter, a system comprising a blood filter and the use of a blood filter or system for the removal of substances from whole blood or blood components.According to the invention, a blood filter comprises an inlet (2), an outlet (3) and at least first fibers disposed between the inlet (2) and the outlet (3) for filtering a fluid being communicated between the inlet (2) and the outlet (3), wherein each of the first fibers comprises at least one groove extending in the longitudinal direction of the fiber.