Objective: Given the increasing interest in the effect of isoflavones on menopause-related symptoms and diseases related to menopause/aging combined with the growing body of published literature on isoflavones, much of which presents conflicting data, The North American Menopause Society (NAMS) established a goal to develop an evidence-based consensus opinion on the role of isoflavones in menopausal health. Design: NAMS appointed a panel of clinicians and researchers acknowledged to be experts in the field of isoflavones. Their advice was used to assist the NAMS Board of Trustees in developing this consensus opinion. Results: Many animal and human studies have evaluated the health effects of isoflavones on menopause-related symptoms and diseases related to menopause/aging. However, data are inconclusive regarding whether the observed health effects in humans are attributable to isoflavones alone or to isoflavones plus other components in whole foods. The most convincing health effects have been attributed to the actions of isoflavones on lipids. Studies have associated isoflavones with statistically significant reductions in low-density lipoproteins and triglycerides as well as increases in high-density lipoproteins. Although some data seem to support the efficacy of isoflavones in reducing the incidence and severity of hot flashes, many studies have not found any difference between the isoflavone recipients and the controls. Inadequate data exist to evaluate the effect of isoflavones on breast and other female- related cancers, bone mass, and vaginal dryness. Conclusions: Although the observed health effects in humans cannot be clearly attributed to isoflavones alone, it is clear that foods or supplements that contain isoflavones have some physiologic effects. Clinicians may wish to recommend that menopausal women consume whole foods that contain isoflavones, especially for the cardiovascular benefits of these foods; however, a level of caution needs to be observed in making these recommendations. Additional clinical trials are needed before specific recommendations can be made regarding increased consumption of foods or supplements that contain high amounts of isoflavones. (C) 2000, The North American Menopause Society.