Among the variety of symptoms of the postmenopausal syndrome joint pain seems to be an important problem for the patient as well as for her doctor. Because of the excellent response of the hormone substitution therapy it is asked if the synovial membrane is a target organ for oestradiol. Biopsies from the knee joint of ten women (not having any hormone therapy) - excised during knee joint surgery - were examined. Only in two cases oestrogen-receptors were found. Accordingly the synovial membrane cannot be seen as a direct target organ for oestradiol and so other mechanisms must play a role in the pathogenesis of postmenopausal joint pain.