Response to endocrine therapy and its relationship to the clinical features of the disease were studied in 84 Egyptian patients with inoperable, locally advanced or metastatic breast cancer. Twenty-four premenopausal patients were treated by oophorectomy with or without concurrent prednisolone. Only one of 20 evaluable patients achieved an objective response. Median time to progression for premenopausal patients was 3 months. Sixty postmenopausal patients received tamoxifen 10 mg twice daily either alone or with prednisolone. Fourteen of 57 (25%) evaluable patients achieved an objective response (four complete remission, 10 partial remission). Median duration of response was 13 months and median time to progression for all postmenopausal patients was 5 months (range 1-30 months). The outcome for postmenopausal patients was similar to that found in a parallel study at Guy's Hospital, London. The response rate for premenopausal Egyptian patients was, however, disappointing and lends support to the claim that breast cancer in Egyptian women is particularly aggressive.