Hysteroscopy is a procedure that may appear minimally invasive, but may result in potentially disastrous complications. A hysteroscopy requires the insertion of a hysteroscope into the uterine cavity and the installation of a suitable distention medium for the visualization of the endometrium. Fluid overload due to the absorption of distention media during hysteroscopy can cause mild to severe complications, including hyponatremia, hypoosmolarity, nausea, vomiting, headache, arrhythmia, blindness, confusion, seizure, cerebral edema, brain herniation, and death. We report a case of a 41 year-old female patient who underwent elective hysteroscopic myomectomy under general anesthesia. Approximately 4 hours after the beginning of the surgery, the patient's serum sodium concentration dropped to 109 mM. She was treated with furosemide and recovered without sequelae.