Platelet rich plasma and/or platelet concentrate is prepared by placing whole blood in a first chamber of a sterile processing disposable having two chambers. The processing disposable is subjected to a first centrifugation to separate red blood cells, and the resulting platelet rich plasma supernatant is decanted to the second chamber. The processing disposable is subjected to a second centrifugation to concentrate platelets. A volume of the platelet poor plasma supernatant in the second chamber is removed, and the platelets are re-suspended in the remaining plasma. The second chamber may contain anticoagulant to preclude aggregation of the platelets.
