Background: Myeloid cells express microparticles that could increase the expression of adhesion molecules including P-selectin. We aimed to evaluate the level of soluble P-selectin (sP-selectin) and prothrombin fragment 1 + 2 (F1 + 2), and to determine correlation of sP-selectin with leukocyte count and F1 + 2 levels in acute myeloid leukemia (AML) and chronic myeloid leukemia (CML) patients. Methods: Patients with newly diagnosed AML (n = 25), CML (n = 13), and controls (n = 17) were recruited in this study. The diagnosis of AML and CML is based on 2001 WHO and/or FAB criteria. Levels of sP-selectin and F1 + 2 were determined using enzyme-linked immunosorbent assay kits (Behring ELISA Processor-III® and Behring Enzygnost F1 + 2). Results: sP-selectin was significantly elevated in CML patients compared to AML patients (p = 0.001). Levels of F1 + 2 in AML and CML patients were significantly increased in comparison to controls (p < 0.001 and p = 0.043). Levels of sP-selectin were significantly correlated to leukocyte count (r = 0.437; p = 0.029) and F1 + 2 (r = 0.436; p = 0.029) in AML patients. Conclusions: AML and CML patients had an increased tendency to thrombosis. While CML patients had higher platelet and/or endothelial activation, hypercoagulable state are more pronounced in AML patients. © 2021, The Author(s).