OBJECTIVE To examine the prevalence, natural history, and predictors of hot flushes in older postmenopausal women. METHODS Prevalence, severity, and 3-year change in severity of hot flushes were assessed by questionnaire in 3167 older postmenopausal women with osteoporosis. Logistic regression was used to identify characteristics associated with symptoms at baseline and after 3 years of follow-up. RESULTS At baseline, 375 women (11.8%) reported bothersome hot flushes. Women were more likely to have baseline symptoms if they were less educated (odds ratio [OR], 1.28; 95% confidence interval [CI], 1.06-1.53 per 4-year decrease), more recently menopausal (OR, 1.44; 95% CI, 1.34-1.56 per 5-year decrease), had previously used estrogen (OR, 1.57; 95% CI, 1.23-2.00), or had undergone hysterectomy (OR, 1.51; 95% CI, 1.14-1.99). Hot flushes were also associated with higher body mass index (OR, 1.22; 95% CI, 1.08-1.38 per 1 SD), higher follicle-stimulating hormone levels (OR, 1.34; 95% CI, 1.20-1.51 per 1 SD), lower high-density lipoprotein levels (OR, 1.17; 95% CI, 1.03-1.34 per 1 SD decrease), vaginal dryness (OR, 1.52; 95% CI, 1.19-1.93), and trouble sleeping (OR, 2.48; 95% CI, 1.94-3.16), but not estradiol levels. Of the 375 women with baseline symptoms, 278 contributed 3-year data, and 157 (56.5%) of these women reported persistent symptoms after 3 years. Fewer years since menopause (OR, 1.15; 95% CI, 1.01-1.32 per 5-year decrease) and trouble sleeping (OR, 1.97; 95% CI, 1.19-3.26) were associated with symptom persistence. CONCLUSIONS For a substantial minority of women, hot flushes are a persistent source of discomfort into the late postmenopausal years. Identification of risk factors for hot flushes may help guide evaluation and treatment in this population.