This research project is centered around the effects of exercise on the immune system and cancer. The main focus of the project is myeloid-derived suppressor cells, which are a population of immature white blood cells. These MDSCs suppress T cell function and are often found in patients with cancer. This suppression of T cells severely decreases the strength of a patient’s immune system and also allows for the cancer cells to spread easier. This project tests the effects of exercise on the number of MDSCs and T cells found in patients with cancer. Previous observational studies have shown that exercise prevents risk and reduces symptoms of cancer. The goal of this research is to find direct evidence that correlates the benefits of exercise for patients through data from MDSCs and T cells. Evidence collected by harvesting various mouse spleen and testing T cell proliferation showed that exercise actually increases MDSC potency and decreases T cell count, proving to be unhealthy for the patient. However, due to experimental error, these results may be inaccurate. More research is currently being conducted on this subject in order to prove that exercise can be beneficial for patients with cancer, as it may improve their immunity and reduce symptoms of cancer and its progression.