Diallyl tetrasulfide is an organosulfur compound that has been found in A. sativum and has diverse biological activities, including antimicrobial, antioxidant, and anticancer properties. It is active against the bacteria S. aureus and methicillin-resistant S. aureus (MRSA; MICs = 0.5 and 2 mg/L, respectively), as well as the fungi C. albicans, C. krusei, C. glabrata, A. niger, A. flavus, and A. fumigatus (MICs = 0.5, 4, 2, 1, 2, and 4 mg/L, respectively).It reduces cadmium-induced increases in hepatic levels of thiobarbituric acid reactive substances (TBARS) and increases cadmium-induced decreases in the hepatic activity of superoxide dismutase (SOD1), catalase, GST, and glucose-6-phosphate dehydrogenase (G6PDH) in rats when administered at a dose of 40 mg/kg. Diallyl tetrasulfide is cytotoxic to MCF-7 breast cancer cells (IC = 92 µM) and reduces tumor growth in a BGC-823 mouse xenograft model when administered at doses of 20, 30, and 40 mg/kg for 32 days.