Background: Electrolytes disturbances observed in hypoxic ischemic encephalopathy can further complicate the already asphyxiated babies Serum sodium is one of the most important electrolytes associated with neuronal activity, routinely serum sodium is added after 24 hour of life in maintenance fluid of neonates but we will monitor the changes in our suspected cases earlier so that early intervention should be done to reduce the perinatal mortality and its fatal outcomes. Aim: To determine the association of hyponatremia with hypoxic ischemic encephalopathy in term infants during first 24 hours of life. Methods: Case control study was carried out at Department of Pediatrics, Aziz Bhatti Shaheed Teaching Hospital Gujrat from12th Feb 2018 to 12th Feb 2019. 134 cases and 134 controls were included in the study. Full term babies (>37 weeks) of either gender was included for both cases and controls. Cases were hypoxic ischemic encephalopathy infants who has history of delayed cry at birth of >5 minutes, respiratory distress and moaning. Hyponatremia was labelled if serum sodium levels are below 130 mmol/lit. Matched controls i.e. healthy neonates from same setting were selected for the study. The serum sodium levels were compared between cases and controls. Results: Serum sodium was unequally distributed among cases & controls (Median±IQR 136±5, 139±8, P value using Mann Whitney U test= 0.01). Hyponatremia was also unequally distributed among cases & controls (3.4% vs 0.4%, P value using Fischer exact test = 0.01). Logistic regression analysis using STEP wise analysis proved that the association found regarding hyponatremia/ serum sodium with hypoxic ischemic encephalopathy is not significant after adjusting for weight and gender of the infant. The distribution of birth weight and gender among cases and controls was similar (P value > 0.05). Conclusion: It is concluded that hyponatremia is not associated with hypoxic ischemic encephalopathy in term infants during first 24 hours of life. Keywords: Hypoxic ischemic encephalopathy, Hyponatremia, Serum sodium, Perinatal asphyxia