The aim of this study was to investigate the genotoxic and antigenotoxic effects of Salvia fruticosa (Sf) leaf extract with the absence and presence of S9 mix using sister chromatid exchange (SCE), chromosome aberration (CA) and micronucleus (MN) formation test systems in human peripheral blood lymphocytes (HPBLs) that were treated with 1.5-, 3.0- and 6.0-mu L/mL concentrations for 24- and 48-hour treatment periods. The cytotoxicity of Sf leaf extract was also investigated by calculating the mitotic index (MI), proliferation index (PI) and nuclear division index (NDI). In the absence of S9 mix, Sf leaf extract alone increased SCE frequency at the 48-hour treatment period; however, it induced the CA and MN at all concentrations and at all treatment periods. Sf plus MMC (mitomycin C) synergically induced SCE and CA, except the highest concentration of Sf leaf extract and MMC on induction of SCE. In addition, Sf leaf extract induced the effect of MMC on MN frequency for 24 hours, but it significantly decreased the effect of MMC on MN frequency for the 48-hour treatment period. Sf leaf extract showed a cytotoxic effect by decreasing the MI; however, it did not decrease the PI and NDI. In the presence of S9 mix, Sf leaf extract did not increase the SCE, when compared to solvent control, whereas it reduced the effect of cyclophosphamide (Cyp). Sf leaf extract induced the CA and MN, but could not increase the effect of Cyp on CA and MN formation. Sf leaf extract had no cytotoxic effect; however, it induced the cytotoxicity of Cyp.