Introduction: Hyponatremia is a common electrolyte abnormality in hospitalized patients. It is defined as serum sodium concentration less than 135mEq/L. It occurs due to disruption of sodium and water homeostasis. Clinical presentation varies from asymptomatic patients to ones having seizures and coma. Aims and objectives: To delineate the clinical profile and causes of hyponatremia in patients admitted in the medicine ward, N.M.C.H, Patna. Material and Methods: This study was conducted on 50 patients admitted in medicine ward of tertiary care teaching hospital of Patna, Bihar from February 2019 to July 2019. Patients older than 18 years with serum sodium less than 135mEq/L were included in the study. Detailed history, clinical examination and all necessary investigations were done accordingly. Type of study: Prospective study with detail history taking and clinical examination. Statistical Analysis: Statistical analysis was done by using MS Excel 2007. Results: In the present study 64% were male, and 90% of patients was older than 45 years. Out of all patients 84% were symptomatic, out of which 19% had mild, 35.8% had moderate & 45.2% had severe hyponatremia.. Most common cause was under nutrition (18%) and most common symptom was altered sensorium in 42% of patients. Interestingly 12% cases of hyponatremia gave history of salt restriction. Conclusion: Hyponatremia is commonly encountered electrolyte imbalance in hospitalized patients mostly in tropical countries like India. It can mimic stroke. Most common cause being under nutrition followed by SIADH. Restricted salt intake advised by physicians is also an important factor of it.