Abstract: A haemodialyzer for use in a haemodialysis equipment of partial recirculation type, in which a vast plurality of semi-permeable hollow fibers formed in a bundle are diagonally disposed in a housing with surplus in length so that the ends of the bundle may direct oppositely downward and upward, respectively, and a dialyzate intake and exit are provided in such positions that flow of the dialyzate may effectively traverse the bundle of hollow fibers. With this haemodialyzer, the bundle of the hollow fibers can be sufficiently expanded to spacingly spread the hollow fibers in the housing to attain good contact with the dialyzate and enhance the haemodialysis efficiency, and the priming and blood recovery operations are much facilitated.