Platelets play a critical role in the pathogenesis and prognosis of ACS . They secrete a number of substances that are key mediators of coagulation, thrombosis and atherosclerosis. High-volume platelets have a higher thrombotic potential than small platelets and have concentrated granule contents that are of interest in the development of ACS pathogenesis . Mean platelet volume (MPV) is the most commonly used measure of platelet size and correlates with platelet activity. Platelet distribution width (PDW) is an index reflecting heterogeneous platelet size, whereas the platelet-large cell ratio (P-LCR) is the proportion of large platelets in blood circulation. Generally, higher MPV, PDW and P-LCR are correlated with increased platelet size, although they tend to be overlooked in clinical applications. In fact, these indices, particularly MPV and PDW, correlate with platelet functions.