In vivo protective and alleviative effects of s-allyl cysteine (SAC), s-ethyl cysteine (SEC), s-methyl cysteine (SMC), and s-propyl cysteine (SPC) against alcohol-induced hepatotoxicity in Balb/cA mice were studied. In the preventive study, SAC, SEC, SMC, or SPC, each agent at 1 g/L, was added into the drinking water for 3 wk, and the mice were then treated with ethanol to induce acute liver injury. In the alleviative study, mice were first treated by ethanol followed by the 4 agent treatments for 3 wk. The preintake of these agents significantly attenuated subsequent alcohol-induced lipid oxidation, glutathione (GSH) depletion, and activity reduction of catalase and glutathione peroxidase (P < 0.05); also attenuated were the alcohol-induced elevation of c-reactive protein (CRP), interleukin-6 (IL-6), IL-10 and tumor necrosis factor (TNF)-alpha (P < 0.05). The preintake of these agents also significantly retarded alcohol-induced cytochrome P450 2E1 (CYP2E1) activity increase (P < 0.05). In the alleviative study, posttreatments from the 4 agents restored liver GSH content (P < 0.05); however, only SEC and SPC posttreatments significantly reduced lipid oxidation and alleviated the alcohol-induced elevation of CRP, IL-6, IL-10, and TNF-alpha (P < 0.05). SEC and SPC posttreatments also significantly diminished alcohol induced CYP2E1 activity (P < 0.05). These results support that SEC and SPC could provide both preventive and alleviative effects against alcohol-induced hepatotoxicity through suppression of oxidation and inflammation.