Abstract: Objective To study the genotoxicity of Radix Aconiti Kusnezoffii and Radix Aconiti Kusnezoffii steamed.Methods The Ames test and Comet assay were used to detect the genotoxicity of Radix Aconiti Kusnezoffii and Radix Aconiti Kusnezoffii steamed.Results With and without S9 activation,there was positive result of Radix Aconiti Kusnezoffii and negative result of Radix Aconiti Kusnezoffii steamed.At the dose of 1.25,2.5,5.0 mg/mL Radix Aconiti Kusnezoffii,the tail length were 16.55±7.81,23.68±8.32,30.18±11.35px and the tail DNA% were 13.65±6.21,20.55±8.55,28.72±13.39 px².Compared with the control group,there were significant differences (P<0.01).There was no significant difference between the negative control and the treated groups of Radix Aconiti Kusnezoffii steamed (P>0.05).Conclusion Radix Aconiti Kusnezoffii could cause genotoxicity,while Radix Aconiti Kusnezoffii steamed could not cause genotoxicity.Attenuation of steaming on Radix Aconiti Kusnezoffii is significant.