Abstract: Objective To explore the correlation between IL-22 expression levels in serum and FOLFOX resistant status and to examine weather IL-22 could promote chemoresistance in colorec-tal cancer cells.Methods ELISA were preformed to detect IL-22 expression levels in 60 patients who received FOLFOX adjuvant chemotherapy after radical excision.The chemoresistant effect of IL-22 in colorectal cancer cells with treatment of chemotherapeutic drugs was investigated.Results IL-22 serum levels increased in chemoresistant patients compared with chemosensitive patients.In addi-tion,IL-22 could confer resistance to 5-FU and OXA of SW480 and SW620 cell lines.Conclusion Elevated serum IL-22 levels correlate with FOLFOX chemoresistant condition of colorectal cancer and may be an important factor for chemoresistance.