Oxidative stress is a state of imbalance between reactive oxygen species (ROS), and the ability of the organism to defend against them, leading to progressive oxidative damage. ROS causes oxidation of proteins, DNA and lipids, which may cause direct tissue injury or induce a variety of cellular responses. 8-hydroxy-2'-deoxyguanosine (8-OHdG) is one of the markers for oxidative stress. In this study, we investigated cigarette smoke constituent(s) associated with 8-OHdG formation in human alveolar type 2 epithelium-like adherent cell line A549 induced by whole smoke-bubbled phosphate buffered saline (WS-PBS).Gas vapour phase-bubbled PBS (GVP-PBS) was estimated to have almost the same level as WS-PBS on 8-OHdG induction in the experiment with a reference cigarette, 3R4F. Correlative analyses between the 8-OHdG induction by 9 different sample cigarettes and the amount of each smoke constituent of them showed that each of the carbonyl compounds (formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, crotonaldehyde, methyl ethyl ketone, n-butylaldehyde) had a high correlation with 8-OHdG induction. When A549 cells were exposed to each of the carbonyl compounds in the amount equivalent to that in WS-PBS of 3R4F, acrolein was the only inducer of 8-OHdG. And the index value of 8-OHdG induction (calculated as the ratio of induction by acrolein to induction by WS-PBS of 3R4F) was 1.00±0.10. Furthermore, when A549 cells were exposed to WS-PBS with acrolein in the amount equivalent to that in WS-PBS of 3R4F, similarly, 8-OHdG was induced, and the index value of 8-OHdG induction was 2.00±0.50. These results show that acrolein is a major factor of intracellular 8-OHdG induction in our study, and they also suggest that acrolein induces 8-OHdG without almost any influence from the other smoke constituents.