Abstract: A dialyzer and a dialysis system particularly adapted to fast dialysis and avoidance of contamination or spillage. Adjustable upper and lower clamp units are provided on a central shaft. Means are provided to securely mount a plurality of dialysis bags around the entire periphery of the clamping units and to provide adequate bath circulation through the relatively confined core volume. The individual dialysis bag may be accurately filled or emptied while in a fully installed position on the dialyzer. The circulating pump is a pair of openings in the bottom clamp unit. The top of each bag is always open to receive a syringe needle. The rotating motor is isolated from the bath.