Hypernatremia due to salt gain is generally iatrogenic. This case report presents a 55 year-old woman who was operated because of hepatic hydatid cyst. At the end of the operation, following extubation the patient was unconscious and serum sodium concentration was found to be 185 mEq/ L. The patient was entubated again and transferred to the intensive care unit. When the patient awaked and became conscious at 36th hour in intensive care unit, she was extubated and transferred to ward with serum sodium concentration of 142 mEq/L. The serum sodium concentration should be monitored carefully in hydatid cyst operation, during which hypertonic saline is used for scelosidal effects as general anesthesia can mask neurologic signs due to hypernatremia.