The anticancer effect of Dangyuja (Citrus grandis Osbeck) leaf extract was investigated using SNU-16 human gastric cancer cells. Maximum cytotoxicity was observed from the chloroform fraction (CF) of the extract. Cell death was dose-dependent ($IC_{50}$=ca. 92.15 ${mu}g/mL$), and was characterized by apoptotic body formation and DNA fragmentation. Flowcytometric analysis showed that treatment of CF resulted in a marked accumulation of cells in the sub-G1 phase. The induction of apoptosis was confIrmed by caspase-3 activity assays and immunoblotting using antibodies against Bid, Bcl-2, Bax, poly (ADP-ribose) polymerase, caspase-9, caspase-8, caspase-7, and caspase-3. Analyses of the CF by gas chromatography (GC) and GC-mass spectrometry tentatively identifIed 21 compounds, including linoleic acid, linolenic acid, palmitic acid, ${alpha}$-amyrin, ${gamma}$-sitosterol, dihydrolanosterol, methyl palmitate, and nobiletin. These results provided the fIrst evidence that the CF of a Dangyuja leaf extract induces apoptosis in SNU-16 cells. Our findings may lead to new strategies for the treatment of human gastric cancer.