It has been suggested that physical activity in breast cancer patients can not only improve quality of life. Influences on physical and psychological levels have been evaluated, but effects on the immune system of breast cancer patients are hardly known. A PubMed search identified relevant trials and meta-analyses from 1970 to 2013. This review summarizes the results of international studies and the current discussion of effects of physical activity on the immune system of breast cancer patients. Highlighted are effects of physical activity on the immune system. Seven original articles and 14 reviews included in this review. Two original and the review articles includes other tumor entities besides breast cancer.Evaluated methods such as dose-response relationships for exercise in oncology, hardly exist. Increased immunological anti-cancer activity due to physical activity is probably mediated via an increase in number and cytotoxicity of monocytes and natural killer cells and cytokines.