Abstract: Objective To explore the effect of ADAMTs5 on cartilage degradation by measuring the expression of ADAMTs5 in condylar cartilage of temporomandibular joint osteoarthritis(TMJOA) rats. Methods 32 rats were divided into four groups(control group 1,2week group,control group 2 and 4week group),and each group had 8 rats.Collagenase injection method was used to build up the TMJOA model.Western blot and RTPCR were used to test the expression of ADAMTs5 in protein and mRNA levels respectively. Results No significant changes were observed in the expression of ADAMTs5 in protein levels between the control group and 2week group,but the expression of ADAMTs5 in 4week group increased significantly.Compared with the control group,the expression of ADAMTs5 mRNA in 2week and 4week groups increased to different degrees,which wasn′t in accordance with protein expression tendency. Conclusions The expression of ADAMTs5 increases significantly in the early stage of TMJOA,which indicates that ADAMTs5 may play an important part in the beginning of condylar cartilage degradation.