An approach to the full assessment of new plasmapheresis machines is outlined. This involves testing for changes in donated blood, donors and blood components using fresh donor blood and during full procedures in an animal model prior to performing full procedures in human volunteers. Using this approach, a new centrifugal plasmapheresis machine, the SPC-600, was assessed. No adverse effects associated with the use of the machine were detected in the initial studies. When used for plasmapheresis of volunteers, 500 ml of plasma was obtained in 43 ± 4 min without adverse effects on donors. The plasma product contained normal levels of plasma proteins, including factor VIII, and 20 ± 6 x 10^9/l platelets. There was no evidence of activation of complement or coagulation systems, and the factor VIII yield in cryoprecipitate prepared from single donations of plasma was equivalent to that observed for standard whole blood donations.