This cross sectional descriptive study was carried out in the Department of Cardiology, Mymensingh Medical College Hospital from July 2015 to December 2015, included 50 patients admitted with acute coronary syndrome diagnosed on the basis of history, typical anginal type of chest pain, characteristic electrocardiographic changes and increased cardiac biomarkers. Platelet count (PC), Mean platelet volume (MPV) and platelet distribution width (PDW) were measured using automated hematological analyzer and compared them with 50 age and sex matched healthy controls. All platelet parameter indices - platelet count (PC), mean platelet volume (MPV) & platelet distribution width (PDW) - were significantly raised in patients with ACS. In patients with ACS the mean values of platelet count, MPV & PDW were 352.2×10⁹/L), 13.9fL & 15.6fL, respectively; while in normal healthy control the mean values of these indices were 256.2×10⁹/L), 8.1fL & 10.5fL, respectively. Statistically significant difference in mean values of these indices was found (p value <0.05). Larger platelets are haemostatically more active and are a risk factor for developing coronary thrombosis and subsequent acute coronary events (myocardial infarction and unstable angina). Patients with larger platelets can easily be identified during routine hematological analysis and could possibly benefit from preventive treatment.