CONTEXT: Incidence of breast cancer is very high among women around the world. Breast cancer patients experience cancer-related fatigue at some points during the treatment for breast cancer. Since cancer-related fatigue is of multifactorial origin, there are no evidence-based treatment strategies for fatigue. This study tested the effectiveness of certain pranayama techniques in reducing cancer-related fatigue among breast cancer patients undergoing radiation therapy. AIMS: The objective of this study was to determine the effectiveness of pranayama on cancer-related fatigue among breast cancer patients undergoing radiation therapy as measured by cancer fatigue scale. SETTINGS AND DESIGN: Shirdi Sai Baba Cancer Hospital and Research Center, Kasturba Hospital Manipal. MATERIALS AND METHODS: Study was a randomized controlled trial done among breast cancer patients receiving radiation therapy. STATISTICAL ANALYSIS USED: Demographic characteristics of the participants are presented as frequency and percentage. Comparison of means of cancer-related fatigue between the two groups is done by Mann-Whitney U-test and comparison of pre- and pos t-test means of cancer-related fatigue among the experimental group is done by Wilcoxon sign rank test. RESULTS: There was a significant difference between the two groups with regard to the scores of cancer-related fatigue. The experimental group of patients who performed pranayama along with radiation therapy experienced less fatigue. CONCLUSIONS: Pranayama can be used as a supportive therapy for breast cancer patients undergoing radiation therapy.