Ageing of the skin results from the synergistic effects of intrinsic ageing (due to age and genetic factors), photoageing (due to ultraviolet radiation) and, for women, hormonal ageing (due to oestrogen deficiency in postmenopausal women). Oestrogens receptors and metabolism or inactivation of oestradiol have been demonstrated in the skin, and the pilosebaceous unit is a target for sexual steroids. Could hormonal replacement therapy (HRT) be a treatment for the symptoms of skin ageing (dryness, roughness, burning and atrophy of the skin, itching, cold intolerance, wrinkles, hyperpilosity, alopecia)? In some experimental studies oestrogens increase the activity of fibroblasts and water, hyaluronic acid and collagen dermal contents. Some studies have demonstrated that oestrogen treatment increases skin thickness, mitotic activity of keratinocytes, and dermal collagen content in postmenopausal women. Thus HRT could theoretically treat skin ageing. It has been shown that HRT alleviates some symptoms of skin ageing (dryness of hair and skin) and that flushes disappear. We demonstrated that non-invasive measurements of physical parameters of the skin can reveal increase in skin thickness (+10 to +20 per cent) in women treated by HRT vs non treated, especially in the application area of oestrogen and in the non-sun-exposed areas. In our study HRT alleviated the hyposeborrhoea usually seen after menopause and could contribute to the amelioration of some complaints of post menopausal women such as roughness or dehydrated skin. Hormonal ageing is quantitatively less than actinic ageing, but its treatment is easier. Moreover HRT increases skin thickness, contributing to the prevention of atrophy (with fragile and fading skin) due to intrinsic ageing, and it limits the masculinization of facial hair and skin experienced by women as a sign of ageing. In conclusion HRT treats oestrogen deficiency and can be used to treat skin ageing.