AIM: To investigate the development in women's attitude to hormone replacement therapy, and the change in views concerning positive and negative effects. METHODS: National cohort study based on telephone interviews in 1990 and 1997, of women randomly sampled from the Norwegian telephone book (n=1019 and 1003). The same questions were asked in both studies. RESULTS: In 1997, more women stated radio and television, doctors, friends and relatives as sources of information. The general attitude to hormone replacement therapy had become significantly more positive, and the respondents reported a higher level of information than in 1990. However, some misunderstandings about estrogen therapy still remain; the proportion of women who believed that estrogen treatment reduced the risk for breast cancer increased from 4% in 1990 to 15% in 1997. About one third of women aged 60 or more are current or past users. More than 60% of the women in the youngest age group state that they will consider use of estrogen replacement therapy. About four-fifths of the women in 1997 stated their willingness to use long term estrogen therapy if osteoporosis could be prevented. CONCLUSIONS: Estrogen replacement therapy has become a part of the public debate. A high degree of willingness to use estrogen is demonstrated. The self reported level of information is higher and women are generally more correctly informed about positive and negative effects.