PURPOSE: To determine the prevalence and severity of vasomotor, gynecologic, and other symptoms among breast cancer patients, their health concerns, beliefs about estrogen replacement therapy (ERT), and willingness to take estrogen under medical supervision. MATERIALS AND METHODS: A questionnaire was mailed to 320 women aged 40 to 65 years and diagnosed with in situ or invasive locoregional breast cancer in the years 1988 to 1992. RESULTS: Of 222 eligible respondents, 190 were postmenopausal. The prevalence of symptoms among the postmenopausal women was as follows: hot flashes, 65%; night sweats, 44%; vaginal dryness, 48%; dyspareunia, 26%; difficulty sleeping, 44%; and feeling depressed, 44%. The latter two symptoms increased in frequency with increasing severity of vasomotor symptoms (P for trend < or = .001). Forty-one percent of menopausal women perceived that they had experienced, since their breast cancer diagnosis, a physical or emotional problem related to menopause. Of these women, 50% felt they needed treatment. Overall, 31% of postmenopausal women would consider taking estrogen. Those who perceived that they had experienced a menopausal problem were more likely to consider estrogen than those who did not (42% v 22%, P = .003). The proportions willing to take estrogen increased with increasing severity of symptoms, particularly feelings of depression and sleep disturbance (P for trend = .008 and .007, respectively). Awareness that estrogen decreases the risks of heart disease and osteoporosis was not associated with an increased willingness to take it. However, beliefs that estrogen increases the risks of recurrent breast cancer and uterine cancer were associated with a decreased willingness to take it (P = .003 and .08, respectively). CONCLUSION: Vasomotor symptoms have a significant impact on the quality of life of breast cancer patients. Clinical trials to determine the safest and the most effective ways to relieve these symptoms are needed.