Brenner tumor is a rare ovarian neoplasm which is generally monolateral, more rarely bilateral, and often associated with endometrial disorders related to oestrogenic production. However, there is no considerable evidence that the possible oestrogenic production of this tumor may be the cause of endometrial disorders. A case of bilateral Brenner tumor with endometrial adenocarcinoma in a postmenopausal woman is presented and the features are briefly discussed, with the conclusion that hormone-producing Brenner tumors may exert their promoter effect on the development of endometrial carcinoma causing an imbalance in the oestrogen and progesterone ratio rather than producing a large amount of oestrogen.