A 58-year-old man presented to us through the emergency department with fever, nausea and vomiting since 15 days along with irritability and confusion in his behaviour since 5 days. On admission, his laboratory workup showed a serum sodium of 130 mEq/l (reference range: 135-145 mEq/l), uric acid of 1.4 mg/dl (reference range: 3.4-7 mg/dl) while the rest of his electrolytes were normal and viral markers were negative. Serum osmolality turned out to be 240 mosm/kg (reference range: 285-295 mosm/kg) while his urine osmolality was 496 mosm/kg (reference range: 50-1200 mosm/kg) and fractional excretion of sodium was 1.2%. Chest x-ray, ultrasound abdomen and echocardiography were all unremarkable. 
 A week later, the patient became drowsy, with a decreased level of consciousness and a low Glasgow Coma Scale (GCS) score but was vitally stable. CT scan of brain was done, which showed diffuse mild age-related atrophy of the brain. 
 Later, a lumbar puncture (LP) was performed and cerebrospinal fluid (CSF) analysis showed a protein of 314 mg/dl (normal: <45 mg/dl), lactate dehydrogenase (LDH) of 63 U/ml (reference range: 2-7 U/ml), a total leukocyte count of 490 (reference range: 0-5) with 95% of lymphocytes. CSF culture revealed no growth while the fungal smear and the acid fast bacilli (AFB) PCR turned out to be negative. 
 Thyroid profile and serum cortisol levels were ordered and were within normal ranges. 
 During his admission, he developed a steady fall in serum sodium and on the 14th day of his stay, it was around 116 mEq/l with a high urine output of up to 4 litr/24-h. At this stage, his spot urinary sodium was 178 mEq/l (reference range: 20-40 mEq/l), and spot urine osmolality was 762 mosm/kg. Fluid restriction was tried to rule out SIADH secretion but the patient did not improve on it. Keeping in view the above laboratory findings, a final working diagnosis of tuberculosis meningitis and cerebral salt wasting syndrome was made. 
 The patient was treated with 3% hypertonic saline, mineralocorticoids and anti-tuberculous therapy (ATT), which not only increased his serum sodium to a normal level within 15 days but also improved his condition drastically and he was later discharged. Thus, a final diagnosis of tuberculous meningitis leading to cerebral salt wasting syndrome was made in this patient and the patient is on regular follow-up and doing well on ATT.