Basiliximab is a chimeric monoclonal antibody directed against the alpha chain of interleukin-2 (IL-2) receptors. Given its expected volume of distribution (plasma volume), therapeutic plasmapheresis may be expected to lower serum Basiliximab levels. A 20-mg dose of Basiliximab was given before plasmapheresis. Blood and pheresis fluid samples were obtained to monitor Basiliximab levels. A total of three blood samples were drawn: the first was obtained 4 hours before, the second sample immediately before commencement, and the third 2 hours after cessation of plasmapheresis. A fourth sample was obtained from the removed plasma. There was an appreciable reduction in Basiliximab concentration levels after plasmapheresis. From the change in serum concentration after plasmapheresis, approximately 64.6% of circulating Basiliximab was removed. Plasmapheresis removes substantial amounts of Basiliximab. Therefore, supplemental Basiliximab should be given after plasmapheresis to maintain the desired duration of IL-2R saturation.