A special insert was developed for centrifuge cups in order to prepare leukocyte-poor platelet concentrates from buffy coats by using quadruple citrate phosphate dextrose-saline adenine glucose mannitol systems from different manufacturers. Each centrifuge cup could contain up to 4 sets of double bags allowing the preparation of 24 platelet concentrates per run. Optimal conditions for centrifugation of the buffy coats in the inserts were found to be 6 min at 380 g (2,150 g min). A platelet count of 69 +/- 19 X 10(9) and a leukocyte contamination of 14 +/- 10.5 X 10(6) per platelet concentrate was thereby obtained in a plasma volume of 63 +/- 10.5 ml (mean +/- SD). The method described allows large scale production of leukocyte-poor platelet concentrates from buffy coats in a closed system.