The purpose of the study was to develop a Web site for the middle-aged women and test the usability of the site. Users' need for information were identified via online survey of 189 middle-aged women. It was found that they had various health problems but very few did any health prevention or health promotion activities. A web site for the middle-aged women was developed based on the result of needs assessment. The site includes content on exercise, diet including weight control, osteoporosis, climacteric, aging, breast and cervical cancer. Besides this health information, FAQ on women's health, my health knowledge test, statistics, link to related institutes and web sites, newspaper articles/mass media clips, journal articles, conferences, papers and other educational information were added. The site was developed as a subsystem of the Healthguide(http://healthguide.kihasa.re.kr). As a way of utilizing the homepage, twenty two women aged 40-50 were recruited at a community-based gathering and health promotion education program was conducted. To test the effectiveness of the education, knowledge, attitude and behavior changes of before and after education were compared. There were significant differences of knowledge and behavior in breast cancer, cervical cancer, osteoporosis, menopause and sexual life. It is expected that Web-based women's health information will contribute to women's health promotion and provide an effective learning media for health education.