Hesperidin, known as a flavonoid constituent of citrus, has been known to reduce the proliferation of several cancer cells. We investigated whether hesperidin-induced cell death on SNU-668, human gastric cancer cells. The cytotoxicity of hesperidin on SNU-668 cells was determined by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay at the concentration of 1, 10, 50, and 100 ${mu}M$. Cell viability by hesperidin was 53.18$pm$2.85% of control value at 100 ${mu}M$. The cell death by hesperidin showed apoptotic features, which were confirmed using a combination of 4, 6-diamidino-2-phenylindole (DAPI) staining and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay. In the apoptosis-regulating genes, treatment of hesperidin decreased mRNA expression of B-cell CLL/lymphoma 2 (BCL2), whereas expression of BCL2-associated X protein (BAX) was increased. The mRNA expression and the activity of caspase3 (CASP3), a major apoptotic factor, was significantly increased by hesperidin treatment. These results suggest that hesperidin could induce apoptosis through CASP3 activation on SNU-668, human gastric cancer cells.