Abstract: The normal cyclic endometrium, the endometrium of irregular bleeding which using Norplant for about half a year and 1 year. All endometrial tissues were studied on morphology and sex steroid receptors by immunohistochemistry. It is to research the relationship between the irregular bleeding and sex steroid receptors of endometrium. The results demonstrated that changes of normal cyclic had not showed in endometrium using Norplant. The vessels of endometrium showed break. The lever of ER and PR in endometrium showed decrease in varying degrees. These results suggested that LNG inhibit production of ER and PR in endometrium. For this reason, bioactivities of E and P were inhibited, among which unhealthy grow of vessels is a possible reason for abnormal uterine bleeding.

Key words: Norplant, estrogen receptor, progesterone receptor, abnormal uterine bleeding