Abstract: Objective To study the toxicity of S-brand hair dyes on rabbits.Methods S-brand hair dyes was spread on the skin of rabbits for six months(two application per week).Rabbits were dissected,Sections from liver,spleen,kidney,thymus,lymphnode and heart were detected from microscope after HE staining,and cell cycles were also analysed.Results No carcinoma was found in all of the rabbits dissected.No abnormal changes were found in all the tissues.Immunohis-tochemical study of liver,spleen and thymus node showed that nucleus positivity of P53 in all the three tissues are higher than the normal control group.Cytoplasm positivity of BCL-2 in these three tissues were also higher than the control group.Cell cycle analysis found that all the three tissues(rabbits applied with hair-dyes)have aneuploid except normal diploid.Conclusion S-brand hair-dyes didn't induce carcinoma in the rabbits,but it was a potential carcinogen.