Methods. The study is based on postal questionnaires sent to 23,000 female Danish nurses above the age of 44 years. Out of these 19,953 (86%) responded. The questionnaire gave information on age, use of hormone replacement therapy, use of oral contraceptives, family predisposition and diseases. Duration of hormone replacement therapy was calculated by Cox regression analysis. Chi square tests were used to evaluate differences and 5%, was used as the level of significance.

Results. Overall, 6673 (33%) had ever used hormone replacement therapy. The prevalence was highest in the age group 55-59, where 29.3% were currently using hormones. The must cited reasons for choosing hormone replacement therapy were vasomotor symptoms (62%) and prevention of osteoporosis (44%). Among never users 43% had not experienced climacteric symptoms, 24% found the therapy unnatural, and 22% were afraid of side effects. It was estimated that 70%;, still were using hormones five years after the start of therapy, 57% after ten years, and 48% after fifteen years. Women with a family history of osteoporosis used hormones longer than women without this predisposition.

Conclusions. One third of all the women had ever used hormone replacement therapy and more than half of ever users used the therapy for more than ten years.