BACKGROUND: It is necessary to protect patient from white blood cells (WBC) caused side effects of platelet transfusion by reducing the WBC contamination in single donor platelets (SDPs). Objective of the new software is to improve WBC depletion performance and collection efficiency. Revised software version, LDP Rev. C2 was installed in our MCSR+ (Hemonetics, USA). We compared the newly introduced software version with the previous software LDP Rev. C. METHOD: SDPs were collected from registered and random repeat donors who visited our blood center. After 49 single needle collections by MCSR+ (software LDP Rev. C) were performed, revised software (LDP Rev. C2) was installed and 48 single needle collections were carried out. The platelet count of donors were measured electronically. The target platelet yields were 3.0x10(11). All units of SDPs were tested for platelet yields and residual WBC. And other parameters were also evaluated. RESULTS: The MCSR+ LDP collected platelets with mean platelet yields of 3.3x10(11)(Rev. C) and 3.4x10(11)(Rev. C2). The total processing blood volume and collection time were significantly reduced in Rev. C2. The collection efficiency was also significantly improved in Rev. C2 (64% vs 57%). Residual WBC in all product collected from software Rev. C2 were below 1 106 and 71% of the products revealed residual WBC below 1 105, respectively. Citrate toxicity was not observed during the apheresis by Rev. C2. CONCLUSION: Revised software LDP Rev. C2 in MCSR+ showed improved collection efficiency and leukocyte depletion performance compared to the Rev. C. And optional control of citrate re-infusion rate seemed to reduce donor citrate reactions during the apheresis.