OBJECTIVE: To evaluate the condition of cancer-related fatigue (CRF) in breast cancer patients with chemotherapy and to explore the effect of Yoga on it. METHODS: After the completion of Yoga, 100 breast cancer patients with CRF (CFS>0) were selected and were randomly divided into the Yoga group and the control group (n=50). Patients in the control group only received routine cure and care while patients in the Yoga group received extra Yoga exercise, lasting for 4 months. Cancer fatigue scale (CFS) was evaluated in the 2nd, 4th and 6th round of chemotherapy. RESULTS: At the end, 82 cases qualified for the study, 42 cases for the control group and 40 for the Yoga group. The mean score of body fatigue was 12.67+/-3.46. There was no significant difference in CRF between the Yago group and the control group before the Yoga intervention (P>0.05). After the 4th round of chemotherapy, the mean scores of CFS and body fatigue in the Yoga group were significantly lower than that in the control group (P<0.05). After the 6th round of chemotherapy, the mean scores of CFS, body fatigue and cognitive fatigue in the Yoga group were lower than that in the control group (P<0.05). Repeated analysis of variance showed that the difference in the overall fatigue, body fatigue and cognitive fatigue between the Yoga group and the control group was significant (P<0.05); the time influence on the overall fatigue, body fatigue and emotional fatigue was significant difference between the 2 groups (P<0.05); there were interactions between the effect of Yago and time on the overall fatigue, body fatigue and cognitive fatigue (P<0.05). CONCLUSION: The body fatigue was more serious in breast cancer patients with chemotherapy. Yoga intervention could significantly reduce body fatigue, cognitive fatigue, thus reduce the overall fatigue in breast cancer patients with chemotherapy.