Cerebral salt wasting syndrome (CSWS), characterized by natriuresis, polyuria, and hypovolemia, is a rare complication of central nervous system injury or disease.12-year-old girl was admitted with second attack of nephrotic syndrome (NS). On admission she presents with edema, blood pressure 110/60 mm Hg, proteinuria 145 mg/kg/24h, hypoalbuminemia (1.7 g/dL), GFR 94.4 mL/min/1.73m2, sodium 133 mmol/L. On 5th day the patient developed thrombosis of right subclavian and axillary vein and was treated with recombinant tissue plasminogen activator (0.3 mg/kg/h i.v.). 45 minutes after onset of the infusion severe headache appeared. Computed tomography revealed subarachnoid hemorrhage in a region of left occipital lobe and posterior 1/3 part of sickle of the brain. Control ultrasonography examination revealed resolution of the thrombus. No deficits were found on neurologic examination. Proteinuria subsided on 11th day of hospitalization. After the hemorrhage hypovolemia, hypotension (80/40 - 100/60 mm Hg, heart rate 100/min), polyuria, and pathologic natriuresis (up to 13.0 mmol/kg/24h) were observed. Cerebral salt wasting syndrome was recognized. The girl was supplemented with oral and intravenous sodium (up to 10 mmol/ kg/24h). In following days gradual decrease of diuresis and urinary sodium loss was observed. The patient was discharged home after 41 days with normal diuresis (1.5l/24h) and natriuresis (1.44 mmol/kg/24h).Treatment of thromboembolic complications in children with NS poses a risk of central nervous system bleeding. Serum sodium concentration and diuresis must be strictly monitored in patients with central nervous system lesion, especially in the course of nephrotic syndrome.