Colorectal cancer (CRC) is the third most common cancer and the second leading cause of cancer-related death for adults in the United States. This disease has a poor prognosis, with most patients dying within two years of diagnosis and a 5-year survival rate of just 11%. These rates are in part due to KRAS gene mutations, which are prevalent in 40-45% of CRC patients. These mutations prevent the utilization of standard epidermal-growth factor receptor (EGFR) based therapies, which block intercellular growth and development signals. As a result, novel therapies are being developed to treat KRAS mutant CRC. One such therapy is oncolytic reovirus, a virus that selectively replicates in and kills KRAS mutant CRC cells. Cytokines, intercellular messengers that regulate the immune system and tumor microenvironment, are released into the bloodstream after infected cells burst. However, the effect of the cytokines created and released as a result of reovirus infection is not well documented. Therefore, the aim of this study was to detect and quantify cytokine changes as a result of treatment of oncolytic reovirus. An enzyme-linked immunosorbent assay (ELISA) was used to quantify the number and type of cytokines released into the bloodstream of patients treated with reovirus at various time points. Data was recorded in Microsoft Excel and statistical analysis was performed using the platform. This experiment demonstrated that there were statistically significant changes in the following cytokine levels: IFNa2, VEGF, IL-8, MIP-1a, and IL-6. It is not apparent that these changes were useful in the treatment of KRAS-mutated mCRC, highlighting reoviruses' inefficiency as a stand-alone treatment in human models.