Objective To study the toxicity of benzene combining with formaldehyde on reproductive cells in mice.Methods Male mice were randomly divided into different groups:three experimental groups with different doses of benzene combining with formaldehyde(mg?kg~(-1))(10+10,50+50 and 100+100),control group and vegetable oil group(n=10).After 8 weeks by oral poison,the mice were killed,testis was weighed,sperm count was peformed,the rate of sperm deformation was counted and the SOD activity was measured.Results The quantities of sperm in various poison groups were obvious decreased and the rate of sperm deformation were obvious increased with dose increasing.Compared with control group,they both had obvious difference(P