Citri Reticulatae Viride Pericarpium (CR) has been used traditionally in Korea to promote the Liver Qi activity and the function of digestive system. We investigated whether the immature peels of Citrus reticulata Blanco (Rutaceae) induced cell-death on SNU-C4, human colon cancer cells. Cytotoxicity of CR was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The cell death was identified as apoptosis using 4,6-diamidineo-2-phenylindole (DAPI) staining and terminal deoxy-nucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay. The expression of pro-apoptotic gene, Bax, was increased and the expression of anti-apoptotic gene, Bcl-2, was decreased by CR-treatment. The expression and activity of major apoptotic gene, caspase-3 was significantly increased by CR-treatment. Considering the above results, CR could induce the apoptosis on SNU-C4, human colon cancer cells via Bax-related caspase-3 activation. And it might provide the experimental data for the future clinical use of CR on colon cancer.