Abstract: A dialyser with a housing includes a pair of inflow and outflow pipes for ood and dialysis solution, and a tubular ring body formed from a plurality of hollow filaments joined to one another at their ends and positioned in the housing such that one pair of the pipes is in communicating relationship with open ends of the hollow filaments and the other pair of the pipes communicates with the interstices between adjacent filament forming said tubular ring body. The invention also provides a dialyser cartridge and a method of manufacturing such cartridge.