Nicotine is a major pharmacologically active component of cigarette smoke. Excessive cigarette smoking is harmful to lung. Sejin-Eum (SJE) I is composed of various Oriental medicines, and SJE II is SJE I plus seeds of Avena sativa (Gramineae) that reduces the craving for cigarette in man. In this study, we have examined whether an aqueous extract of SJE I/II inhibits nicotine- or cigarette extract (CE)-induced cytotoxicity in human embryonic lung fibroblast, MRC-9. Assessment of cell viability using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide colorimetric assay indicated that SJE I/II (500 and 1000 microg/ml) not only inhibited nicotine-induced cytotoxicity but also had significantly proliferous effect on MRC-9. However, SJE I/II had little effect on inhibition of CE-induced cytotoxicity. These results suggest the possibility that the use of SJE I/II may be useful for improvement of many symptoms by nicotine.