Several recent papers have suggested the role of HRT in the development of breast cancers. From the data base of the Institut Curie we compared the clinical characteristics, histoprognosis factors and survival of a cohort of 6737 patients recorded between 1988 and 1999 in which 1482 declared having receive HRT for more than 6 months. Surgical procedure, locoregional recurrence, metastasis, disease free and global survival were compared bet the patient who received an HRT versus the patients who didn't receive this treatment Mammographic diagnosis was more frequent in the HRT group and the age at diagnosis was smaller (p < 10(-4)). Cancers diagnosed in the HRT group were smaller and had a more favourable biologic profile as well as there were more lobular carcinomas and the conservative treatment was more frequent (p < 10(-4)). Mean follow up was 97 months. Recurrence free survival was not different in the two groups but the metastasis free and global survival were better in the HRT group. HRT remained an independent prognostic factor in a multivariate analysis. In western countries the increasing incidence of breast cancer concerns pre as well as post menopausal women. HRT cannot be considered as the only responsible of this augmentation.