Objective: Endometrial cancer prognosis is related to stage, histology, myometrial invasion, and lymphovascular space invasion. Several studies have examined the association between pretreatment thrombocytosis and patient outcomes with contrasting results regarding prognosis. Our aim was to evaluate the association of pretreatment platelet count with outcomes in endometrial cancer patients. Methods: This is an Israeli Gynecologic Oncology Group multicenter retrospective cohort study of consecutive patients with endometrial cancer, who underwent surgery between January 2002 and December 2014. Patients were grouped as low risk (endometrioid G1-G2 and villoglandular) and high risk (endometrioid G3, uterine serous papillary carcinoma, clear cell carcinoma, and carcinosarcoma)....