The ADVIA 120/2120 Hematology System provides a number of novel parameters of platelet activation. Although the effects of anticoagulant in the blood-collection tube, short-term storage, and ambient temperature on these parameters have been documented in the literature, the effects of long-term storage and the material of the blood-draw tube have not been investigated. We therefore compared platelet activation parameter values obtained with the ADVIA 120 for 50 paired blood samples collected into BD Medical Systems' Vacutainer K(3)EDTA glass tubes and Vacutainer K(2)EDTA Plus plastic tubes and analyzed within 4 hours and after 24 hours following venipuncture. We found a statistically significant but clinically irrelevant decrease (less than 1%) in mean platelet component (MPC) concentration in plastic compared with glass for blood samples analyzed within 4 hours of draw. Reanalysis of the samples after 24 hours showed a clinically and statistically significant increase in mean platelet volume and significant decreases in MPC, platelet component distribution width, and mean platelet mass. These storage-induced changes were of equal magnitude for both tube types. We conclude that the use of plastic versus glass blood-draw tubes should have no clinically significant effect on the parameters of platelet activation on the ADVIA 120/2120 system and that the changes in platelet activation parameters continue to be present at 24 hours.