From November 2013 to November 2015 among 3 410 patients underwent hysteroscopy in our hospital, 14 developed hyponatremia during operation, and the incidence was 0.41%.Among 311 patients underwent hysteromyomectomy, 8 developed hyponatremia during operation, and the incidence was 2.6%.Among 476 patients underwent endometrectomy, 1 developed hyponatremia during operation, and the incidence was 0.2%.For the 8 patients underwent curettage, 62 patients underwent trans-cervical resection of adhesion and 11 patients underwent trans-cervical resection of uterine septa, the incidence of intraoperative hyponatremia was not calculated because the number of patients was less than 100.All the 14 patients with hyponatremia suffered from severe gynecological diseases or were diagnosed with a larger volume of lesion.Among the patients developing hyponatremia during hysteromyomectomy, 4 presented with large submucous myomas (maximum diameter≥3 cm), and 4 presented with medium-sized submucous myomas (1 cm≤maximum diameter≤3 cm); the maximum diameter of the intrauterine residue >2.5 cm in 2 patients, endometrial thickness was found in 1 patient, 2 patients were diagnosed with severe intrauterine adhesions, and the last one was a complete septate uterus.The duration of operation was (92±43)min, irrigation fluid deficit was 2 200(4 000)ml, and irrigation fluid pressure was 120(40) mmHg, which were higher than the level of the corresponding parameters in routine hysteroscopy.Hemodynamic instability (changes in blood pressure and heart rate >20% of the baseline value) and severe hypoxia (SpO2 95%). One patient did not develop hemodynamic instability or hypoxia.Blood natrium, potassium, chloride, calcium ion, hemoglobin and hematocrit were significantly lower during operation and on the right postoperative day than before operation (P<0.05). Blood natrium returned to normal after treatment with furosemide and/or 1%-3% sodium chloride, and no permanent neurologic damage was found in all the patients.In conclusion, hysteroscopic hyponatremia was affected by factors such as surgical type, lesion size, surgical time, irrigation fluid deficit and pressure, and the major clinical manifestations included neurological abnormalities and fluid overload. Key words: Hyponatremia; Intraoperative complications; Hysteroscopy