Objective:This study aimed to evaluate the acute and chronic cytotoxicity and genotoxicity of 2,6-dichloro-1,4-benzoquinone (2,6-DCBQ).Methods:NIH3T3 cells were exposed to 2,6-DCBQ for 3 and 72 h,and relative cell viability was calculated.NIH3T3 cells were treated with different concentrations of 2,6-DCBQ for 24 h.The solvent and positive controls were dimethyl sulfoxide (DMSO) and 0.5 μmol/L ethylmethylsulfone,respectively.The values of Olive tail moment were measured by comet assay.NIH3T3 cells were then simultaneously treated with 5 μg/mL cytochalasin B and different concentrations of 2,6-DCBQ.The solvent and positive controls were DMSO and 1 μmol/L mitomycin C,respectively.Micronucleus rates were calculated after 48 h.Results:The half lethal doses of 2,6-DCBQ in NIH3T3 cells were 64.93 μmol/L for 3 h and 13.46 μmol/L for 72 h.The values of Olive tail moment in the 7.5 and 10 μmol/L groups were significantly higher than those in the solvent control (P ＜0.05).Moreover,the micronucleus rates in the 10 and 15 μmol/L groups were significantly higher than those in the solvent control (P＜0.05).The results of comet assay and micronucleus test showed a dose-response relationship.Conclusion:2,6-DCBQ exhibited strong cytotoxicity and induced DNA and chromosomal damage in NIH3T3 cells.