BACKGROUND: Depression, anxiety, and fatigue are among the most significant problems that influence the quality of life of patients with breast cancer who receive adjuvant chemotherapy. Although evidence has shown yoga to decrease anxiety, depression, and fatigue in patients with cancer, few studies on the effects of yoga have targeted patients with breast cancer. Yoga interventions should be tested to promote the psychological and physical health of women with breast cancer. PURPOSE: This study examines the effectiveness of an 8-week yoga exercise program in promoting the psychological and physical health of women with breast cancer undergoing adjuvant chemotherapy in terms of depression, anxiety, and fatigue. METHODS: A sample of 60 women with nonmetastatic breast cancer was recruited. Participants were randomly assigned into either the experimental group (n = 30) or the control group (n = 30). A 60-minute, twice-per-week yoga exercise was implemented for 8 weeks as the intervention for the participants in the experimental group. The control group received standard care only. RESULTS: Analysis using the Johnson-Neyman procedure found that the yoga exercise reduced overall fatigue and the interference of fatigue in everyday life for the experimental group participants. Significant reductions were obtained after 4 weeks of intervention participation for those experimental group patients with relatively low starting baseline values (baseline item mean value .05) or anxiety (F = 2.7, p > .05). CONCLUSIONS/IMPLICATIONS FOR PRACTICE: The 8-week yoga exercise program developed in this study effectively reduced fatigue in patients with breast cancer but did not reduce depression or anxiety. Oncology nurses should strengthen their clinical health education and apply yoga to reduce the fatigue experienced by patients with breast cancer who undergo adjuvant chemotherapy.