The results of several studies suggest that acute platelet-rich plasmapheresis decreases blood loss and allogeneic blood product transfusion requirements in cardiac surgery patients. We designed a randomized, prospective study to determine whether acute plateletrich plasmapheresis decreases blood loss and allogeneic transfusion requirements in primary cardiac surgery patients. Forty patients were randomized to a control or pheresis group. The pheresis group had platelet-rich plasmapheresis performed before cardio-pulmonary bypass (CPB) and the platelet-rich plasma (PRP) was returned after CPB. The control group was managed in the normal fashion without pheresis. All patients had serial coagulation studies, hemoglobin, and platelet counts determined intra- and postoperatively. Chest tube drainage and transfusion requirements were recorded. There were no differences in the coagulation tests, platelet counts, chest tube drainage, or allogeneic blood product transfusion requirements between the two groups at any time. The authors conclude that the use of acute platelet-rich plasmapheresis in primary cardiac surgery patients does not decrease chest tube drainage or the need for allogeneic blood transfusions.