Abstract: Objective: To investigatethe effect of occlusal traumatism on the high mobility group box protein 1(HMGB1) expression in ovariectomized(OVX) mice's periodontal tissues. Methods: Twenty-four female Kunming mice were divided into four groups randomly:①control(CON);②occlusaltraumatism(OT);③ovariectomized(OVX);④ovariectomized+occlusal traumatism(OVX+OT).The mice in OVX and OVX+OT group receivedovariectomy at the beginningof the experiment, and then the OT and OVX+OT were subjected toocclusal traumatism at the 7th week after the surgery. All the mice were killed to make paraffin sections at the 8th week. Immunohistochemistry were applied to study the expression of HMGB1, a computerized image analysis system was used to analyze the result. Results: The HE staining showed that the periodontal membrane fibers in micesubjected toocclusal traumatism were disorganized and torn. More TRAP-positive osteoclasts were found in OVX+OT group than other groups.The expression of HMGB1 in OVX+OT group was the highest.Both TRAP-positive osteoclasts and HMGB1-postive cells in eitherOT or OVX groups were a little more than that in CON group. However there was no significant difference between the two groups. Conclusion: HMGB1 may play a role in the periodontal tissue remodeling of OVX mice subjected to occlusal traumatism.