Background: To assess serum potassium levels in subjects with acute myocardial infarction.Materials & methods:A total of 40 subjects were enrolled. Demographic, clinical and treatment data were obtained. AMI was diagnosed. Serial serum potassium levels during hospitalization were obtained from the patients’ medical records and were reviewed. The results were analysed using SPSS software.Results:Out of 40 subjects, number of subjects with lower potassium levels i.e<3.0 mEq/L are 3 and death rate is 33.4 % whereas death rate is less in patients with potassium levels in the range of 3.5 to 4.5 mEq/L.Conclusion:There is a U shaped relationship between potassium levels and mortality rate of myocardial infarction.