Forty-six evaluable postmenopausal patients with locally advanced, inoperable T3-T4 breast carcinoma were treated with tamoxifen 10-20 mg twice daily for a period at least 6 weeks. Eight patients (17%) had an objective response at the primary tumor site after 6 weeks of treatment. Improvement of response with a further single tamoxifen therapy was observed in 7 patients, resulting in an overall objective response in 14 of 46 (30%). Median duration of response was 8 months (range 2-24). No response was obtained in the 5 patients with inflammatory signs. Toxicity of treatment was minimal. Medial survival was 10 months (responders 17.5, non-responders 9). Tamoxifen seems to be safe and effective treatment for locally advanced breast cancer without inflammatory signs in postmenopausal women.