To examine preventive health practices in older women, we conducted computer-assisted telephone interviews with 1082 women aged 50-80 who were enrollees of Group Health Cooperative of Puget Sound (June-November 1995; 80.3% response rate). We sought to describe the women's reasons for initiating, discontinuing, or not initiating hormone replacement therapy (HRT). HRT use was categorized as current (42.5%), past (20.9%), or never (36.6%) based on the interviews. The reasons most frequently cited by current users for initiating HRT were menopausal symptoms (47.3%), osteoporosis prevention (32.4%), and physician advice (30.3%). The most frequently cited reasons for quitting HRT were side effects (26.6%), physician's advice (22.9%), fear of cancer (15.4%), and not wanting menstrual periods or bleeding (15.2%). Of past users, 53.8% reported stopping HRT on their own, and 46.2% did so at their physician's advice. The reasons most commonly cited by never users for not initiating HRT were that hormones were not needed (49.9%) and that menopause is a natural event (17.9%). Among never users, 33.1% reported considering HRT, only 46.6% discussing it with their provider, and 5.0% being given an HRT prescription they did not fill. Many women made decisions about HRT independent of interactions with health care providers. Better understanding of the beliefs and decisions that influence women's choice to use or not use HRT is needed to develop more effective counseling strategies.