The aim of the present study is to investigate the potential differences between the effects on breast cell proliferation of natural progesterone combined with percutanous estrogen versus a combination of oral conjugated equine estrogens (CEE) + medroxyprogesterone acetate (MPA). Therefore, to confirm or refute whether these different types of combined HRT have different in vivo effects in the short term on proliferation and apoptosis in breast cells from normal postmenopausal women. 80 patients, 40 in each group, are randomized to either of treatments. Every woman is her own control. Medium needle biopsy is performed before and after 2 months of treatment and markers for proliferation, apoptosis as well as estrogen- and progesterone receptors are analyzed.