Daphne genkwa Sieb.et Zucc. is a well-known medicinal plant. This study was designed to investigate the anticancer effects of total flavonoids in D. genkwa (TFDG) in vitro and in vivo. HT-29 and SW-480 human colorectal cancer cells were cultured to investigate the anticancer activity of TFDG. In addition, the ApcMin/+ mouse model was applied in the in vivo experiment. Results of the cell experiment revealed that TFDG possessed significant inhibitory effects on HT-29 and SW-480 human colorectal cancer cells (both p < 0.01). Furthermore, our in vivo data showed that after treatment with TFDG, there was a significant increase in life span (both p < 0.01) and tumor numbers were reduced in the colon (both p < 0.01), which was supported by the data of tumor distribution, body weight changes and organ index. Our results also indicated that expressions of interleukin (IL)-1α, IL-1β, IL-6, granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor in gut tissue were downregulated by treatments of TFDG, and immunity cytokine secretions in the serum were regulated after oral administration of TFDG. Taken together, these findings suggested that TFDG has a potential clinical utility in colorectal cancer therapeutics, and TFDG's action is likely linked to its ability to regulate immune function and inhibit the production of inflammatory cytokines. Copyright © 2015 John Wiley & Sons, Ltd.