ABSTRACT Background: Magnesium deficiency leads to the progression of atheromatous plaques which occurs as a result of hyperlipidemia. Myocardial infarction is one of the most common causes of mortality where its prognosis depends upon various factors. This study is designed to know the contribution of magnesium levels in the serum of acute MI patients to the occurrence of arrhythmias. Materials & Methods: This observational cross-sectional study was conducted in the Medicine Department, Govt. Medical College, Barmer, Rajasthan, India during one year period. A total of 30 patients of AMI were enrolled in this study. They were diagnosed with AMI on the basis of clinical symptoms, cardiac biomarker levels and/or Electrocardiography (ECG) findings. For all the patients, serum magnesium levels on day 1 and day 5 were measured and its association was observed with the clinical consequences. Results: In this study group of 30 cases, 25 were males and 5 were female patients with a male-female ratio of 5:1. The mean value of serum magnesium on day-1 those with arrhythmias is 1.62±0.23 those without arrhythmias is 2.03±0.49 (p<0.001). There is a significant difference in the magnesium level in patients with arrhythmias and without arrhythmias. The serum magnesium level in patients with arrhythmia on Day-5 is 1.93±0.26 and in those without arrhythmia is 2.52±0.61. The difference between these two is found to be statistically significant with p- value (p<0.001). Conclusion: We concluded that patients with acute myocardial infarction with low magnesium levels are more prone to develop ventriculararrhythmias compared to those who are having normal magnesium levels.