OBJECTIVES: Previous research has found that yoga can enhance quality of life and ease menopausal symptoms of breast cancer survivors. The study examined whether self-esteem mediated the effects of yoga on quality of life, fatigue and menopausal symptoms, utilizing validated outcome measures.STUDY DESIGN: This is a secondary analysis of a randomized controlled trial comparing the effects of yoga with those of usual care in 40 breast cancer survivors who suffered from menopausal symptoms. All participants completed all 3 assessments (week 0, week 12, and week 24) and provided full data. MAIN OUTCOME MEASURES: Outcomes were measured using self-rating instruments. Mediation analyses were performed using SPSS. RESULTS: Self-esteem mediated the effect of yoga on total menopausal symptoms (B=-2.11, 95% BCI [-5.40 to -0.37]), psychological menopausal symptoms (B=-0.94, 95% BCI [-2.30 to -0.01]), and urogenital menopausal symptoms (B=-0.66, 95% BCI [-1.65 to -0.15]), quality of life (B=8.04, 95% BCI [3.15-17.03]), social well-being (B=1.80, 95% BCI [0.54-4.21]), emotional well-being (B=1.62, 95% BCI [0.70-3.34]), functional well-being (B=1.84, 95% BCI [0.59-4.13]), and fatigue (B=4.34, 95% BCI [1.28-9.55]). Self-esteem had no effect on somatovegetative menopausal symptoms (B=-0.50, 95% BCI n.s.) or on physical well-being (B=0.79, 95% BCI n.s.). CONCLUSIONS: Findings support the assumption that self-esteem plays a vital role in the beneficial effect of yoga and that yoga can have long-term benefits for women diagnosed with breast cancer and undergoing menopausal transition.