Those composing temporomandibular joint (TMJ) complex such as the temporal bone, the disc and the mandibular condyle perform their own functions with organic relation. The retrodiscal tissue is the main area of pain induction and contributes to compositional change of synovial fluid. If displacement of the disc lasts long time, not only adaptive changes, but also destructive or degenerative changes may happen. It was reported that these changes and symptoms appear mostly to female rather than male and especially, in the case of patients suffering from TMJ disorder, a large quantity of female sex hormone is found in the joint synovium. And that may play a role in bone resorption and inflammation. Also, the frequency and the intensity of pain perception for female is reported to be much more than for male. In this study, we investigated the expression extents of estrogen receptors (ER) and progesteron receptors (PR) in retrodiscal tissue with immunohistochemistry among the patients received TMJ surgery and compared with MRI findings and surgical findings. We report the relations between the expression of ER in retrodiscal tissue and the pathological change in TMJ, such as inflammation, internal derangement and osteoarthritis.