A gravity based blood fractioning device comprising a component for receiving whole blood which is connected to an inlet chamber of a filter and wherein said filter possesses separate outlet chambers connecting to a receptacle for cellular blood components and a receptacle for blood plasma and wherein each receptacle is connected to said filter via a conduit and wherein the conduit connected to the cellular blood component receptacle is of sufficient length to allow said receptacle to be raised up sufficiently high as to reverse the flow of cellular blood components back through the filter a second time to obtain a second degree of filtration of the cellular blood components and thereby increase the volume of plasma extracted.
