We describe a patient with severe hypernatremia and uremia caused by paranoid adipsia who was treated successfully with hydration and hemodialysis. A previously healthy 40-year-old woman developed the paranoid idea that her water was poisoned, so she refused to drink any water. On admission, her blood urea nitrogen was 208mg/dL, creatinine 4.90mg/dL, serum osmolality 452mOsm/L, serum sodium 172mEq/L, urine specific gravity ≥1.030, urine osmolality 698mOsm/L, and urine sodium/potassium/chloride 34/85.6/8mEq/L. We diagnosed her with uremic encephalopathy and started intravenous dextrose, but the sodium correction was incomplete. She underwent two sessions of hemodialysis to treat the uremic encephalopathy and hypernatremia, and recovered fully without neurological sequelae. Although the standard treatment for severe hypernatremia is hydration, hemodialysis can be an additional treatment in cases of combined uremic encephalopathy.