In this retrospective study, 162 breast cancer patients were analysed in whom brain metastases had been diagnosed clinically between 1969 and 1995 at a single institution. 145 patients were treated with megavoltage irradiation (60 cobalt or 6MV) of the whole brain using opposed fields. The most common applied schedule consisted of 30 Gy in 15 daily fractions over 3 weeks. 10 patients underwent surgery and 17 patients received symptomatic treatment only. The median age was 50 years (range 30-78 years). 81 of 162 patients (50%) were premenopausal. Women younger than 40 years of age had a shorter survival (median 12 weeks) than those of all other groups (median 29 weeks). Median survival was 82 weeks for the 10 surgical patients, 26 weeks for the 145 patients treated with radiotherapy and 5 weeks for the patients who received symptomatic (corticosteroid) therapy only. Patients with solitary metastases treated with radiation alone (45 patients) had a survival of 44 weeks versus 23 weeks in patients with multiple brain metastases. Multivariate stepwise regression analyses revealed Karnofsky Index, dose of radiation (P < 0.001), solitary metastases (P < 0.04) and primary tumour size (P < 0.04) as significant prognostic factors for survival.