AIMS: The aim of this study is to compare the effects of yoga program with supportive therapy counseling on mood states, treatment-related symptoms, toxicity, and quality of life in Stage II and III breast cancer patients on conventional treatment.METHODS: Ninety-eight Stage II and III breast cancer patients underwent surgery followed by adjuvant radiotherapy (RT) or chemotherapy (CT) or both at a cancer center were randomly assigned to receive yoga (n = 45) and supportive therapy counseling (n = 53) over a 24-week period. Intervention consisted of 60-min yoga sessions, daily while the control group was imparted supportive therapy during their hospital visits. Assessments included state-trait anxiety inventory, Beck's depression inventory, symptom checklist, common toxicity criteria, and functional living index-cancer. Assessments were done at baseline, after surgery, before, during, and after RT and six cycles of CT. RESULTS: Both groups had similar baseline scores. There were 29 dropouts 12 (yoga) and 17 (controls) following surgery. Sixty-nine participants contributed data to the current analysis (33 in yoga, and 36 in controls). An ANCOVA, adjusting for baseline differences, showed a significant decrease for the yoga intervention as compared to the control group during RT (first result) and CT (second result), in (i) anxiety state by 4.72 and 7.7 points, (ii) depression by 5.74 and 7.25 points, (iii) treatment-related symptoms by 2.34 and 2.97 points, (iv) severity of symptoms by 6.43 and 8.83 points, (v) distress by 7.19 and 13.11 points, and (vi) and improved overall quality of life by 23.9 and 31.2 points as compared to controls. Toxicity was significantly less in the yoga group (P = 0.01) during CT. CONCLUSION: The results suggest a possible use for yoga as a psychotherapeutic intervention in breast cancer patients undergoing conventional treatment.