Unsaturated carbonyl compounds such as acrolein (ACR) and methyl vinyl ketone (MVK) are major cytotoxic factors in the gas phase extract of cigarette smoke. ACR and MVK induce cell membrane damage and cell death through protein kinase C and NADPH oxidases. We have previously reported that several antioxidants such as reduced glutathione (GSH) and N-acetylcysteine (NAC) can suppress ACR- and MVK-induced cell membrane damage and cell death, although the molecular mechanism has remained to be clarified. In this study, we have elucidated the mechanism for suppression of ACR- and MVK-induced cell injury by antioxidants. The molecules with thiol group such as GSH, NAC, and cysteine effectively suppressed cell membrane damage and cell death induced by cigarette smoke gas phase, ACR, and MVK. The results of HPLC and MS showed that GSH and NAC directly reacted with ACR and MVK. Cysteine and cysteine derivatives suppressed ACR-induced protein carbonylation. Current results suggest that GSH, NAC, and cysteine directly reacted with ACR and MVK, and suppressed unsaturated carbonyl compounds-induced cell damage by preventing protein carbonylation.