The method involves producing a flow path between a vein (10) and a removal bag (12) to transport a pre-determined blood removal quantity from the vein into the removal bag. The flow path is interrupted and another flow path is produced. A hollow fiber filter (14) is arranged in the latter flow path to transport plasma from the fiber filter to a plasma bag (16). The removal bag is arranged above the fiber filter in a height that is adapted to porous size of the filter for producing hydrostatic pressure, where citrate-phosphate-glucose-solution is supplied to the removal bag.
