Abstract: A hemofilter is disclosed for use in a continuous arterio-venous hemofiltration ("C.A.V.H") having a bundle of hollow fibers in which the lengths of the particular fibers of the bundle are greatest for those hollow fibers closest to the blood ports of the hemofilter and, preferably, would continuously decrease in length and be least for those particular fibers furthest from the blood ports. The fibers would, preferably, be secured in a bundle to one another by means of an epoxy resin, or similar substance, which did not interfere with the passage of blood through the hollow fibers of the system. Heparin may be chemically bound to the hollow fibers of the invention.