A total of 76 nulliparous women who had been hospitalized for minor operations, classified according to age group (by decade from 20s to 60s) and 118 postmenopausal women randomly allocated to one of four groups were studied. In all, 312 skin biopsies were taken from the lower abdomen at 0 and 12 months and the skin collagen changes noted. Collagen content decreased significantly with age beyond the 40s (P < 0.001) and after the menopause (P < 0.01). The decrease was preventable by the use of hormone replacement therapy. All the therapeutic regimens induced increases in skin collagen content, whereas in the control group a significant decrease was observed (P < 0.05).