Background: Coronary artery disease (CAD) is caused by atherosclerosis and its complications. Total leukocyte count and platelet have different roles in the pathogenesis of ST- segment elevation myocardial infarction (STEMI). Aims and Objective: To evaluate the prognostic significance of haematological parameters in myocardial infarction patients by comparing with healthy subjects. Materials and Methods: This prospective study was carried out on 48 cases diagnosed with ST elevation myocardial infarction (STEMI) and 48 normal healthy subjects from June 2018 to July 2019 in department of pathology and cardiology at Narayana Medical College & Hospital. Results: Of the total, 48 cases, 35 (72.91%) are men, 13(27.09%) are women with myocardial infarction and 48 controls of which 32(66.67%) are men and 16(33.33%) are women. Neutrophil-lymphocyte ratio (NLR) and platelet –lymphocyte ratio (PLR) were found to be significantly higher in STEMI group than the controls (p<0.005), 8.669±2.06 vs 2.09±0.45 and 210.05 ± 40.93vs 117.01±29.41. Mean platelet volume (MPV), Platelet distribution width (PDW) are higher in cases when compared to healthy subjects (13.79±3.36 vs 8.48±1.23) and (15.85±0.96 vs 14.71±1.16). Conclusion: Mean platelet volume (MPV), platelet distribution width (PDW), Neutrophil - lymphocyte ratio (NLR), Platelet-lymphocyte ratio (PLR) are considered to be an independent risk factors for myocardial infarction.