<p class="abstract"><strong><span lang="EN-US">Background:</span></strong><span lang="EN-US"> Hyponatremia is a common electrolyte abnormality in hospitalised patients. Incidence varies from 1% to 40%. It is common in the elderly, mainly owing to impaired water and electrolyte balance in response to diet, drugs and environmental changes. This study is to evaluate clinical features, aetiologies and outcome in patients with hyponatremia (Sr. Na &lt;120 mmol/L at the time of admission).</span></p><p class="abstract"><strong><span lang="EN-US">Methods: </span></strong>An observational study was conducted in 76 patients admitted in Kamalnayan Bajaj Hospital, Aurangabad from August 2013 to August 2014. All patients having their serum sodium concentration less than 120 mmol/L were included in the study. History, examination and relevant details were taken. Outcome was noted. Student’s t-test, chi square test and Fisher’s exact test were applied for statistical analysis.</p><p class="abstract"><strong><span lang="EN-US">Results:</span></strong><span lang="EN-US"> In the present study, mean age of the patients was 59.4% years. 43% patients were euvolemic, 38% hypervolemic and 19% hypovolemic. Nausea (54%) was most common gastrointestinal while drowsiness (42%) was the most common neurological symptom. Etiology of hyponatremia was multifactorial in 76% cases. Use of diuretics (53%) was the most common etiological factor. SIADH was suspected in nine patients. Mortality was 21%. Most common comorbid conditions were hypertension (51%) and diabetes mellitus (42%).</span></p><p class="abstract"><strong><span lang="EN-US">Conclusions: </span></strong>Hyponatremia is a common electrolyte abnormality in hospitalised patients. There is an increasing tendency for it to occur with increasing age, hypertension, diabetes mellitus and use of drugs (diuretics). Nausea, vomiting and drowsiness are the commonest symptoms. Mortality is high, though not directly related to serum sodium levels. Hyponatremia acts as a poor prognostic marker of primary disease.</p>