A 51-year-old postmenopausal woman was referred to our hospital for treatment of ER-positive recurrent breast cancer. The patient had lung and pleural metastases with pleural effusion from breast cancer. She was treated with anastrozole, a 3rd-generation aromatiase inhibitor. The efficacy of the treatment was definite: the multiple metastatic lung lesions showed a partial response after 5 months' treatment, and reached a complete response after 14 months' treatment. The patient experienced no adverse effects with this therapy. Anastrozole therapy is a useful treatment for postmenopausal woman with ER-positive recurrent breast cancer.