The present study included 12 whole blood bags, 12 platelet rich plasma platelet concentrates (PRP-PCs) and 13 single donor platelet pharesis (SDPP) units; all were stored up to 5 days for whole blood bags at 6˚C and for PCs and SDPP units at 22˚C in a platelet shaker incubator. Samples were assayed for CD41 as specific platelet marker and CD62p as a marker for platelet activation by flowcytometry, platelet factor 4 (PF-4) & β thromboglobulin (β-TG) as platelet secretory products by (EIA). Samples were withdrawn at different storage times (on day 0,3,5). Results and statistical analysis revealed a significant increase in CD62p%, PF-4 and β-TG in all groups throughout the storage period and this increase was much higher in whole blood bags compared to PCs and SDPP units and also there was a significant decrease in CD41% in all groups throughout the storage period which was prominent in whole blood compared to PCs and SDPP units and in PCs compared to SDPP units. In conclusion: data obtained indicated that SDPP units were shown to resist the hazards of platelet activation and the element of storage time to a better degree than the other two competitors characterized by highest CD41 positive platelets, and least content of activation markers CD62P positive platelets and PF-4 and β-TG levels.