In order to investigate the possible use of platelet parameters on the ADVIA 120 hematologic analyzer as the routine quality control indicator for preparation and storage of platelets, platelet parameters, pH and CD62P expression were determined in stored platelet concentrates. Platelet component distribution width (PCDW) was decreased progressively on days 1 and 3 of storage for 5 days when compared with 0 day. PCDW correlated with CD62P expression on unstimulated platelets and the difference in CD62P expression following agonistic stimulation (a measure of functional reserve). Mean platelet component (MPC) was decreased on day 1 of storage. It did not however, show a progressive decrease over storage time and did not correlate with CD62P, although MPC has been known to be a useful screening test for platelet activation. Therefore, PCDW is considered to be a simple, convenient and cost-effective quality indicator for determining the viability and storage lesion of platelets for transfusion.