A 56-year old female patient who was undergoing follow-up for cervical cancer in our oncology center was presented to the emergency center with anxiety and excessive thirst. The initial serum sodium level of the patient exceeded 200mEq/L, rising up to 238mEq/L during hospitalization. The extremely severe hypernatremia was caused by patient's wrong belief that bay salt would cure the cancer. The patient was treated with hypotonic solution and finally with appropriate hydration, she was fully recovered without any neurological complications.