Objectives To analyze the mechanisms and implications involved in the generation of platelet associated antibodies in cancer patients.Methods HLA IgG antibody from 116 cancer patients who had received repeated platelet transfusion (more than 3 times) was screened by ELISA and the GTI QUICKSCREEN kit. The positive samples from the initial screening were confirmed for HLA and HPA antibodies using the PAKPLUS reagent. Patients with antibodies were observed for symptoms and clinical effectiveness of platelet transfusions. Results A total of 44 cases of HLA IgG antibody were screened out of 116 samples, with an antibody rate of 37.93%. Among those 44 samples, 18 were confirmed to contain anti-HLA-Ⅰantibody, 8 with anti-HPA antibody, 10 with both anti-HPA and anti-HLA antibodies, and 8 were not identified. The occurrence of antibodies was positively correlated to the times of platelet transfusions and correlated to the improvement of clinical symptoms (P