Abstract: Objective：To evaluate the efficacy of narrow band imaging （NBI） in diagnosis of the endometrial diseases. Methods：A total of 400 patients were observed under NBI and WL hysteroscopy，and the findings were compared with pathologic examinations. Results：For differentiating normal from abnormal endometrial histopathology，the use of NBI showed a significantly higher specificity （93% vs. 78%） and sensitivity （98% vs. 95%） and Youden index（0.91 vs. 0.74）. Conclusions：Overall，the number of correct diagnoses with NBI was significantly higher than with WL. The use of NBI improved the reliability of diagnostic hysteroscopy. The high specificity and the low number of false negativity may reduce the number of unnecessary biopsies or of those performed in wrong areas.

Key words: Hysteroscopes, Hysteroscopy, Endometrial hyperplasia, Endometritis, Endometrial neoplasms