Abstract: The cytotoxicity and genotoxicity of Sauropus androgynus L. Merr.(SA) was assessed using human cell lines MRC-5 and Hep G2 in vitro. METHODS：MRC-5 and Hep G2 cells were treated with uncooked SA homogenate at 1 450，725，363，181，90.6，45.3，22.6，11.3 mg/ml for 24 h. Then the cytotoxicity was studied using the neutral red intake test and the 50% inhibition concentration (IC50) was obtained. According to the cytotoxicity results，Hep G2 cells were treated with SA at 72.5，36.3，18.1 mg/ml，and in vitro micronuclei (MN) incidence was analysed. The number of cells with MN was recorded and the frequency was calculated. RESULTS：IC50 was 133.1 mg/ml in MRC-5 cells and 185.1 mg/ml in Hep G2 cells which were all treated for 24 h with SA. The cytotoxicity of SA on MRC-5 cells originated from human lung was more severe than Hep G2 cells originated from human liver. There was no significant difference between the groups of various SA concentrations and the negative control (P>0.05) in Hep G2 cell micronuclei test. CONCLUSION：SA homogenate could selectively damage MRC-5 cells originated from human lung，compared to Hep G2 cells originated from human liver. No obvious damage to genetic materials could be observed in Hep G2 cells.

Key words: Sauropus androgynus L. Merr., cytotoxicity, micronuclei