Medicinal benefits of Allium are attributed to sulfur-containing compounds, collectively known as organosulfur compounds (OSCs), derived from garlic and other Allium vegetables. Most common OSCs are diallyl sulfide (DAS), diallyl disulfide (DADS), diallyl trisulfide (DATS) and ajoene. Epidemiological studies have suggested cancer risk reduction with increasing intake of Allium vegetables and this association has been documented for prostate, gastric, esophageal, breast and colorectal cancers. In vitro studies with different cancer cell lines, in vivo studies with chemically-induced carcinogenesis and tumor xenograft animal models proved that OSCs have chemopreventive as well as chemotherapeutic activity. DATS and other OSCs mediate their anticancer effects by altering the metabolism of carcinogens, by inhibiting cell cycle progression, inducing oxidative stress leading to DNA damage and consequently inducing apoptosis. Recent studies have found that these OSCs also possess anti-angiogenic activity. This review discusses the cancer chemopreventive and chemotherapeutic effects of DATS and other related OSCs from Allium vegetables in relevant models and its beneficial implications for humans.