Background: A variety of apheresis devices are now available on the market for plateletapheresis. We compared two apheresis instruments (Fenwal Amicus and Fresenius COM.TEC) with regard to processing time, platelet (PLT) yield and efficiency, and white blood cell (WBC) content. Material and Methods: Donors undergoing plateletpheresis were randomly separated into two groups (either the Amicus or the COM.TEC cell separator). Results: In the pre-apheresis setting, 32 plateletpheresis procedures performed with each instrument revealed no significant differences in donors' sex, age, weight, height and total blood volume between the two groups. However, the pre-apheresis PLT count was higher with the COM.TEC than with the Amicus (198 x 10(3)/mu l vs. 223 x 10(3)/mu l; p = 0.035). The blood volume processed to reach a target PLT yield of = >= 3.3 x 10(11) was higher in the COM.TEC compared to the Amicus (3,481 vs. 2,850 ml; p < 0.001). The median separation time was also significantly longer in the COM.TEC than in the Amicus (61 vs. 44 min; p < 0.001). 91 and 88% of the PLT products collected with the Amicus and the COM.TEC,respectively, had a PLT count of = 3.3 x 10(11) (p = 0.325). All products obtained with both instruments had WBC counts lower than 5 <-> 106, as required. There was no statistical difference with regard to collection efficiency between the devices (55 +/- 15 vs. 57 +/- 15%; p = 0.477). However, the collection rate was significantly higher with the Amicus compared to the COM.TEC instrument (0.077 +/- 0.012 x 10(11) vs. 0.057 +/- 0.008 x 10(11) PLT/min; p < 0.001). Conclusion: Both instruments collected platelets efficiently. Additionally, consistent leukoreduction was obtained with both instruments; however, compared with the COM.TEC instrument, the Amicus reached the PLT target yield more quickly.