Purpose: Adjuvant radiation therapy (RT) in breast cancer treatment has been proven to enhance outcome, improving recurrence and mortality rates. RT, however, gives rise to unfavourable side-effects, fatigue the most frequent. The aim of this study was to assess the effect of exercise (and different exercise prescription parameters) during adjuvant RT on fatigue among breast cancer patients. Quality of life was a secondary outcome. Search Methodology and Selection Criteria: Randomised controlled trials that investigated the effect of exercise during adjuvant RT on fatigue for breast cancer patients were searched using MEDLINE, EMBASE, Google Scholar, CINAHL, AMED and ClinicalTrials.gov. Reference lists of included studies and relevant reviews were also checked. Results: Nine studies (802 participants) were included. A meta-analysis, including results for 738 participants, revealed that exercise was statistically more effective at reducing fatigue than the control intervention (SMD- 0.46, 95%CI-0.79 to-0.14). Statistically significant benefits of supervised, combined aerobicresistance exercise on fatigue were achieved. Further research is required to confirm this finding and determine the effect of alternative exercise modes. Conclusions: Exercise during adjuvant RT can be considered beneficial in breast cancer patients. Supervised, combined aerobic-resistance exercise shows promise in alleviating fatigue with further investigation into alternative exercise modes required. (C) 2017 Elsevier Ltd. All rights reserved.