AbstractThe aim of this study was to analyze the impact of various donor and machine parameters on PLT yield in 127 PLT apheresis procedures, to optimize PLT yield achieving clinical and economic advantages. One hundred and twenty‐seven apheresis procedures were analyzed. Age, gender, volume processed, Hb, and PLT precounts were included as donor predicting variables. AC infusion rate, processing time, and plasma volume collected with PLTs were assessed as machine parameters. We evaluated the post‐transfusion effectiveness in 23 patients with thrombocytopenia, studying the effect of PLT dose, ABO group, and PLT storage time. Females gave higher yields, compared to males, P < 0.01. PLT yield correlated positively with PLT precount (r = 0.512), and TBV (r = 0.404), and negatively with donor preapheresis Hb (r = −0.306). Processing time and AC infusion rate had a positive impact on PLT yield. Post‐apheresis decrease in PLT count was 53.6 ± 26.3 × 1011. Donors with Hb ≥ 12 g/dl, donated safely. Most of the complications were citrate related (13.4% of all procedures). PLT increments in transfused patients correlated positively with the number of units transfused (r = 0.41), and negatively with PLT storage days (r = −0.342). PLT increments in patients receiving ABO‐compatible PLTs were 75% higher, compared to the increments in patients receiving incompatible PLTs. PLT count and volume processed were the main predictors of PLT yield. Increasing the processing time, the AC infusion rate, or the volume of plasma obtained with PLTs can increase PLT yields. High PLT dose, short storage time, as well as ABO compatibility should be considered during PLT transfusion. J. Clin. Apheresis, 2007 © 2007 Wiley‐Liss, Inc.