Introduction Chest pain is one of the most common causes of all emergency department applications. 1 In the United States, approximately 8 million patients are admitted to the emergency department because of chest pain each year, from whom only 15%-25% are diagnosed with acute coronary syndrome (ACS). 2 Considering the fact that ACS is fatal but it is largely possible to provide full healing when diagnosed early, rapid and accurate management of patients with chest pain becomes even more important. In ACS, as a multifactorial disease, endogenous and exogenous risk factors are involved in pathogenesis. Platelet activation leads to an increase in platelet consumption in the area of atherosclerotic plaque rupture. This leads to the release of large-sized platelets from the bone marrow during an acute coronary event. 3 Large platelets are relatively younger and contain more intracellular granules, meaning that platelets have more thrombogenic potential. 4 Hemogram is an easy and inexpensive test that can be performed easily in all health systems, including primary care centers. Platelet large cell ratio (P-LCR) test is one of the test parameters that is routinely calculated and given in the hemogram test, and expressed as the ratio of platelets with platelet volume greater than 12 femtolitres (fL). The ratio of normal P-LCR, i.e. large-volume platelets to all platelets, should be less than 30%. 5 Larger platelets which are reflected by high P-LCR levels indicate higher circulating cholesterol and triglyceride levels in serum. 6 There are many studies in the literature that explore the relationship between platelet parameters in the hemogram and the ACS. Although the mean platelet volume was studied frequently in these studies, the P-LCR test was studied in a small number of the studies. 6,7 In one of these studies, Dehghani et al investigated the relationship between platelet parameters between unstable angina (UA), ST elevation MI (STEMI), and non-ACS chest pain. 8 In this study, a significant correlation between P-LCR value elevations and ACS was