Objective: studying on the quality of plateletpheresis separated by three machines: Trima, Comtec, Haemonetic. The effect of some factors of donors on the quality of plateletpheresis. Subjects and Methods: 30 plateletpheresis were collected randomly from each machine to study on quality. 148 donors, studied on the effect of some factors of donors on the quality of plateletpheresis. Results: The number of platelets in the plateletpheresis obtained from the Trima, Comtec, Haemonetic machines were 2.91 + or - 0.18, 2.85 + or - 0.40 and 3.10 + or - 0.29 x 1011/unit, respectively. The number of the highest remaining erythrocyte was 0.02 + or - 0.03 x 1012 /L
leukocytes was 0.18 + or - 0.25 x 109 /L. Obtained plateletpheresis volume was ensured.