Backgrounds: Amygdalin (D-mandelonitrile B-gentiobioside), a cynogenic compound, is found in sweet and bitter almond, Persicae semen, and Armeniacae semen. Aqueous extract of amygdalin was made from Armeniacae semen and used in this study. Objectives: Apoptosis is a very important mechanism in cancer treatment. In the present study, it was investigated whether amygdalin induces apoptotic cell death in human COLO 201 colon cancer cells. Materials and Methods: For this study, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, 4,6diamidino-2-phenylindole (DAPI) staining, terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay, flow cytometric analysis, reverse transcription-polymerase chain reaction(PR-PCR), western blot analysis, and caspase-3 enzyme assay were performed on COLO 201 cells. Cells treated with amygdalin exhibited several characteristics of apoptosis. Results: Amygdalin treatment enhanced Bax expression and suppressed Bcl-2 expression in COLO 201 cells. Amygdalin also was shown to increase the caspase-3 activity. Conclusions: Amygdalin induces apoptotic cell death via Bax-dependent caspase-3 activation in COLO 201 cells.