Background: Lower respiratory tract infection is an infection beneath the larynx which includes: Pneumonia, Wheeze associated LRTI , Bronchiolitis and Empyema. Study aimed to determine frequency of hyponatremia in children and an attempt has been made to correlate the possible electrolyte disturbances in children suffering from severe pneumonia and their outcome. Material & Method: This retrospective descriptive study was conducted among the patients attending the Department of Paediatrics of YMCH, Mangalore, during the period of one year from January 2021 to December 2021. All children between 1month to 5yrs and with signs and symptoms of LRTI are included in the study. Presence of severity of hyponatremia was compared with type of pneumonia and other lower respiratory tract infections based on x-ray findings. The data were collected regarding duration of hospital stay in PICU or Ward, need of oxygen, need of ventilator support and duration of mechanical ventilator and the final outcome of the patient in terms of complications, discharge and death and will be assessing hyponatremia in terms of morbidity and mortality in pneumonia patients in comparison to patients of pneumonia with normonatremia. Data were entered into Microsoft excel and the statistical analysis was performed using statistical software SPSS version 23.0. Results: The present study documented equal distribution of the patients in hyponatremia and normonatremia group, with male preponderance in the study. There was significant higher incidence of the hyponatremia among the patients diagnosed with pneumonia compared to the patients diagnosed with empyema and bronchiolitis. There is no significant associated noted in the present study with the hyponatremia and poor outcome. Conclusion: The present study documented higher incidence of the hyponatremia among the patients with lower respiratory tract infection, the hyponatremia was more common among the children with pneumonia compared to the other lower respiratory tract infections in the study. Also the study did not find the significant effect on the outcome of the patients.