A myocardial infarction happens when blood flow stops or decreases to the coronary arteries of the myocardial muscle, resulting in damage to the heart muscle. Magnesium is important electrolyte plays vital role in suppressing arrhythmias during myocardial ischemia and during reperfusion. Potassium is the most abundant cation of intracellular fluid. A significant correlation between hypokalemia and ventricular fibrillation is recorded. Calcium plays a vital role in myocardial muscle contraction. Aim of this study is to study serum levels of magnesium, potassium and calcium in acute myocardial infarction patients. This was a prospective case control study conducted in Prathima Institute of medical sciences Nagunur, Karimnagar, Telangana state, India between January 2015 to December 2015. A total 50 acute myocardial infarction patients and 50 normal age and sex matched healthy controls selected for study. Serum magnesium estimated by colorimetric xylidyl blue complex method, serum potassium estimated by ion selective electrode method and serum calcium by OCPC method. Statistical analysis carried out using statistical software SPSS version 16 and p-value < 0.05 considered statistically significant. Serum levels of magnesium, potassium and calcium were significantly decreased in acute myocardial infarction patients when compared healthy controls and is statistically significant (<0.05). The above study suggested decreased serum level of key elements such as magnesium, potassium and calcium in acute myocardial infarction patients when compared to healthy controls. Estimation and correction of these elements may play a pivotal role in management of patients with acute myocardial infarction.