Abstract: The plasmapheresis assembly includes a novel Y connector valving structure to replace conventional tube clamps. This valving structure eliminates dead spaces for blood to collect and clot and provides a fluid tight seal during heat sterilization without causing deformation of the tubing for the assembly. Possible erroneous connection of assembly components with resultant contamination is eliminated by the use of unique mating connectors in place of spikes or needle connectors. These mating connectors are employed in a simple and efficient blood bag construction to provide substantially rigid access ports to facilitate rapid manual manipulation of the blood bags.