The study was to explore the change of coagulation factor VIII and IX activities in the platelet suspension collected by platelet apheresis during storage at 22 degrees C. 18 samples of platelet concentrates were collected by the cs-3000 plus and stored at 22 degrees C and then FVIII: C, FIX: C activities were detected at 0, 12, 24, 48, 72, 96, 120 hours respectively by SYSMEX CA-1500. The results showed that FVIII: C activity was (100.51 + 44.02)% at 0 hour, and then decreased dramatically to 10% - 40% of primary level from 12 to 120 hours, while FIX: C activity was (120.93 +/- 20.50)% at 0 hour and decreased to 10% - 35% of primary level from 24 to 120 hours. In conclusion, FVIII and FIX in the platelet concentrates stored at 22 degrees C could keep their biological activities at physiologically high levels.