Abstract: A dialyzer cartridge includes a resilient gasket defining a central hollow area, and first and second cross members affixed in and extending between the interior side walls of the gasket to divide the hollow area into first, second and third portions. The ends of a plurality of hollow fibers are embedded in respective cross members to extend across the second portion of the hollow between the first and third portions. A first fluid is introduced into the first portion to be transported through the fibers to the third portion and a second fluid is introduced into the second portion to flow about the fibers and thereby facilitate the process of dialysis between the interior and exterior of the fibers. The second portion of the hollow is sealed from the first and third portions by a pair of plates secured together with the gasket sandwiched therebetween.