Abstract: It is intended to provide a blood purification membrane having excellent performance and showing little elution of blood and little adhesion of blood proteins or platelets. The above object can be achieved by using a moisten membrane, which is free from any membrane pore-sustaining agent and has a high water permeation dose and a large pore size, and lessening the pore size by drying the membrane after desolvation.

Abstract: It is intended to provide a blood purification membrane having excellent performance and showing little elution of blood and little adhesion of blood proteins or platelets. The above object can be achieved by using a moisten membrane, which is free from any membrane pore-sustaining agent and has a high water permeation dose and a large pore size, and lessening the pore size by drying the membrane after desolvation.

Abstract: A bundle of permselective hollow fibers is disclosed, containing a plurality of filaments having a fineness of from 0.05 to 20 denier at a filament-to-hollow fiber ratio of from 2 to 3000. The filaments intermingle with the hollow fibers substantially lengthwise over the length of the hollow fibers, and substantially all of the filaments each engage with at least one of the hollow fibers, thereby placing the hollow fibers into an inseparable bundle. The bundle has not only a high packing ratio of hollow fibers, but also an effective arrangement for efficiently exerting a high performance of each hollow fiber. The bundle can be constructed into a fluid separator, which is useful for dialysis, ultrafiltration, osmosis, reverse osmosis, pressure separation of gas mixtures and the like.