Hyponatremia is one of the common electrolyte abnormalities in intensive care unit settings. Hyponatremia may lead to an increased hospital stay, morbidity and mortality. Hyponatremia can occur due to a variety of iatrogenic as well as part of complex disease processes during hospital admission. The objective of this study was to find the prevalence of hyponatremia in patients admitted to the intensive care unit of a tertiary care centre. A descriptive cross-sectional study was conducted in the intensive care unit of a tertiary care centre for a duration of six months from 12 August 2015 to 11 January 2016. Ethical approval was taken from the Institutional Review Committee (Reference number: 124/6-11-E/072/073). Data was collected from hospital records. Patients with abnormal serum sodium levels after admission to the intensive care unit were included in the study. Hyponatremia was defined as a serum sodium level less than 135 mEq/L. Convenience sampling methods were used. Point estimate and 95% Confidence Interval were calculated. Among 102 patients, the prevalence of hyponatremia was found to be 21 (20.59%) (12.74-28.44, 95% Confidence Interval). The prevalence of hyponatremia in patients admitted to the intensive care unit was higher than in other studies conducted in similar settings. cross-sectional study; prevalence; sodium.