Hyponatremia is the most common electrolyte disorder among hospitalized patients and has been associated with increased mortality. The aims of the study are to study the incidence, clinical manifestations and symptomatology and clinical conditions which are associated with hyponatremia and analyse clinically possible cause of hyponatremia. This was a study of 100 patients admitted in the ICU of tertiary care hospital with serum sodium levels <135 mEq/L and age >15 years over a period from November 2019 to April 2021. Descriptive statistical analysis has been carried out in the present study. Among the 100 patients studied, 62% were males and 38% were females. The conscious patients have mild hyponatremia while moderate to severe hyponatremic patients came with altered sensorium. 44% patients were having renal causes while 21% patients had cardiac condition. The mortality was 14% in this study. Critically-ill patients suffer from hyponatremia due to various causes, including kidney disease, diuretics, heart failure, cirrhosis of the liver as well as infections. It presents with various symptoms and is linked to high morbidity and mortality in patients. Therefore, physicians must find signs and symptoms of patients in order to reduce mortality and morbidity and provide better care to the patients.