Hyponatremia is a common electrolyte disorder encountered in patients of neurological disorders which is usually either due to inappropriate secretion of Antidiuretic hormone (SIADH) or cerebral salt wasting syndrome (CSWS). We conducted this study in a tertiary care hospital to determine the incidence and etiology of hyponatremia in patients of stroke admitted in the hospital.It was a prospective study done over a period of two years that included established cases of stroke diagnosed on the basis of clinical history, examination and neuroimaging. 1000 stoke patients were evaluated for hyponatremia (serum sodium <130 meq/l). The data was analysed using Chi-square test using SPSS (Statistical package for social science) software.Out of 1000 patients, 353 patients had hyponatremia. Out of this 353 patients, 238 (67%) had SIADH and 115 (33%) had CSWS. SIADH was seen in 83 patients who had ischemic stroke and 155 patients of hemorrhagic stroke. CSWS was found in 38 patients with ischemic stroke and 77 patients with hemorrhagic stroke. Statistical analysis revealed that hyponatremia significantly affects the outcome of stroke especially when it is due to CSWS rather than SIADH.Incidence of hyponatremia in our study population was 35%. In patients of hyponatremia 67% were having SIADH and 33% were having CSWS. Overall hyponatremia affected the outcome of stroke especially when caused by CSWS. Therefore close monitoring of serum sodium must be done in all patients who are admitted with stroke and efforts must be made to determine the cause of hyponatremia, in order to properly manage such patients thereby decreasing the mortality rate.