Background: Hospitalized individuals frequently have hyponatremia, which frequently indicates a poor prognosis. It has recently been demonstrated that hyponatremia can predict death in patients with ST-elevation myocardial infarction (STEMI) and is a known predictor of mortality in patients with heart failure. The present study was conducted to assess the effect of hyponatremia in patients with suspected acute coronary syndrome. Materials & Methods: 70 patients of acute myocardial infarction of both genders were selected. Serum potassium and sodium levels were measured upon admission, as well as after 12, 24, and 48 hours. Hyponatremia was considered if sodium level was <135 mEq/L. Results: Out of 70, hyponatremia was present in 28 and absent in 52 patients. Among hyponatremia and non- hyponatremia patients, anemia at admission was seen in 27% and 21%, left ventricular ejection fraction <35% in 22% and 19%, diuretic use before admission was seen in 38%and 31%, coronary artery disease in 54% and 50%, myocardial infarction in 20% and 18%, hypertension in 67% and 70%, diabetes mellitus in 68% and 36%, smoker were 24% and 20%, congestive heart failure in 16% and 15%, chronic renal insufficiency in 52% and 46%, death or myocardial infarction in 14% and 7% patients respectively. The difference was significant (P< 0.05).Adverse events were maximum in patient with hyponatremia (52%). The difference was significant (P< 0.05).Predictors of death or myocardial infarction at 30 days was age >65 yrs, pulmonary edema at admission, systolic blood pressure <90 mm Hg and hyponatremia. Conclusion: Hyponatremia on admission is associated with 30-day adverse outcome in patients presenting with suspected acute coronary syndrome/non-STEMI.