IMPORTANCE: The expected duration of menopausal vasomotor symptoms (VMS) is important to women making decisions about possible treatments. OBJECTIVES: To determine total duration of frequent VMS (≥6 days in the previous 2 weeks) (hereafter total VMS duration) during the menopausal transition, to quantify how long frequent VMS persist after the final menstrual period (FMP) (hereafter post-FMP persistence), and to identify risk factors for longer total VMS duration and longer post-FMP persistence. DESIGN, SETTING, AND PARTICIPANTS: The Study of Women's Health Across the Nation (SWAN) is a multiracial/multiethnic observational study of the menopausal transition among 3302 women enrolled at 7 US sites. From February 1996 through April 2013, women completed a median of 13 visits. Analyses included 1449 women with frequent VMS. MAIN OUTCOMES AND MEASURES: Total VMS duration (in years) (hot flashes or night sweats) and post-FMP persistence (in years) into postmenopause. RESULTS: The median total VMS duration was 7.4 years. Among 881 women who experienced an observable FMP, the median post-FMP persistence was 4.5 years. Women who were premenopausal or early perimenopausal when they first reported frequent VMS had the longest total VMS duration (median, >11.8 years) and post-FMP persistence (median, 9.4 years). Women who were postmenopausal at the onset of VMS had the shortest total VMS duration (median, 3.4 years). Compared with women of other racial/ethnic groups, African American women reported the longest total VMS duration (median, 10.1 years). Additional factors related to longer duration of VMS (total VMS duration or post-FMP persistence) were younger age, lower educational level, greater perceived stress and symptom sensitivity, and higher depressive symptoms and anxiety at first report of VMS. CONCLUSIONS AND RELEVANCE: Frequent VMS lasted more than 7 years during the menopausal transition for more than half of the women and persisted for 4.5 years after the FMP. Individual characteristics (eg, being premenopausal and having greater negative affective factors when first experiencing VMS) were related to longer-lasting VMS. Health care professionals should counsel women to expect that frequent VMS could last more than 7 years, and they may last longer for African American women.