Abstract: ObjectiveTo find out the genotox icity of main stream and side stream of the cigarette.MethodsThe micronuclear test in polychromaticer ythrocytes(PCEs)of bone marrow and the sperm abnormality test in Wistar mice were performed.ResultsThe sperm abno rmality rate and the micronuclear r ate in main stream and side stream groups were significantly higher than those in black control(P<0.05).In sperm abnormality test,the sperm abnormality rate in main stream and side stream groups and dosage showed dose-response relationships(r=0.995 0,P<0.05).The sperm abnor mality rate and the micronuclear rate in the low,middle,high dosage of side stream were respectively significantly higher than those of main stream(P<0.05).ConclusionMain stream and side stream also have mutagenesis,and the mutagenesis of side stream is stronger than that of main stream.