CONTEXT: Breast cancer patients awaiting surgery experience heightened distress that could affect postoperative outcomes.AIMS: The aim of our study was to evaluate the effects of yoga intervention on mood states, treatment-related symptoms, quality of life and immune outcomes in breast cancer patients undergoing surgery. SETTINGS AND DESIGN: Ninety-eight recently diagnosed stage II and III breast cancer patients were recruited for a randomized controlled trial comparing the effects of a yoga program with supportive therapy plus exercise rehabilitation on postoperative outcomes following surgery. MATERIALS AND METHODS: Subjects were assessed prior to surgery and four weeks thereafter. Psychometric instruments were used to assess self-reported anxiety, depression, treatment-related distress and quality of life. Blood samples were collected for enumeration of T lymphocyte subsets (CD4 %, CD8 % and natural killer (NK) cell % counts) and serum immunoglobulins (IgG, IgA and IgM). STATISTICAL ANALYSIS USED: We used analysis of covariance to compare interventions postoperatively. RESULTS: Sixty-nine patients contributed data to the current analysis (yoga n = 33, control n = 36). The results suggest a significant decrease in the state (P = 0.04) and trait (P = 0.004) of anxiety, depression (P = 0.01), symptom severity (P = 0.01), distress (P < 0.01) and improvement in quality of life (P = 0.01) in the yoga group as compared to the controls. There was also a significantly lesser decrease in CD 56% (P = 0.02) and lower levels of serum IgA (P = 0.001) in the yoga group as compared to controls following surgery. CONCLUSIONS: The results suggest possible benefits for yoga in reducing postoperative distress and preventing immune suppression following surgery.