In a randomised study, 218 patients with advanced breast cancer, resistant to hormone therapy, received either doxorubicin 20 mg every week (Awkly) alone or Awkly combined with high doses (1000 mg daily) of oral medroxyprogesterone acetate (HD-MPA). Of the 210 evaluable patients, the response rates were 26% [95% confidence interval (CI) 18-34%] for Awkly and 38% (95% CI 29-47%) for Awkly + HD-MPA (P = 0.08). There was no significant difference with regard to duration of response. Median survival was 11 months in both groups. Considerable toxicity was seen from HD-MPA, particularly weight gain and fluid retention. The present study provides evidence that, in concordance with preclinical studies and a previous randomised study, interaction between chemotherapy and HD-MPA may exist in breast cancer normally resistant to hormone therapy. For further studies, other gestagens and/or a dose reduction could be investigated.