Allyl disulfide is an organosulfur originally found in garlic that exhibits antioxidative, antiviral, neuroprotective, anti-parasitic, anticancer, and anti-hyperlipidemic activities. Allyl disulfide induces phase II enzymes, inhibits lipid peroxidation, and acts as a radical scavenger. In vitro, allyl disulfide inhibits proliferation of HIV-1, and in vivo, it suppresses growth of Gyrodactylus. In other cellular models, allyl disulfide inhibits 4α-methyl oxidase, suppressing cholesterol synthesis. In Drosophila models of Parkinson’s disease, this compound decreases α-synuclein aggregate-induced neuronal death. In leukemia cells, allyl disulfide induces G2/M phase cell cycle arrest and apoptosis, increases levels of p21, release of cytochrome c, and activation of caspase 3 and PARP, and decreases activation of NF-κB.