Abstract In present study, human lymphocytes were exposed to cigarette smoke condensates (CSCs) at the doses of 25, 50, 75, 100 and 125 μg ml −1 with and without S9, and the cyto-genotoxic effects were detected with CCK-8, cell apoptosis and micronucleus assays. DNA repair kinetics was observed with comet assay. Our results indicated that the cell viability decreased with CSCs doses, the percentages of apoptosis cell and the frequencies of micronuclei increased with CSCs doses, and DNA damage of human lymphocytes induced by CSCs could be basically repaired within 240 min. However, the cytotoxicity induced by CSCs +S9 was significantly lower than that induced by CSCs −S9 in CCK-8 and cell apoptosis assays, and the DNA repair speed in +S9 group was quicker than that in −S9 group. In conclusion, S9 may affect not only the cyto-genotoxicity of CSCs but also the repair process of DNA damage induced by CSCs in lymphocytes.