Abstract: OBJECTIVE: To use the Ames and the HPRT tests，six oxidative hair dyes were tested，and application of the two methods in detecting mutagenicity of oxidative hair dyes was discussed. METHODS: Four dose groups，ranging from 312 to 10 000 μg/dish were set up for the Ames test. mutagenicity was determined by calculating the numbers of reverted mutant colonies. In the HPRT test，V79 cells were cultured in vitro，and 4 dose groups were set up for analysis，with the dose range from 4.88 to 5 000 μg/mL，to determine mutation frequencies of the HPRT sites. RESULTS: With or without an in vitro metabolic activation system in the Ames assay，the numbers of retroactive colonies in the treated groups were more than twice that of the solvent control group，and there was a dose-effect relationship. However，there was no statistically significant difference in cell mutation frequencies between the treated and the control group with or without the metabolic activation system. CONCLUSION: Due to cytotoxicity of the oxidative hair dyes to mammalian cells，the HPRT test was not capable of detecting mutagenicity of the hair dyes. Thus，the Ames test which is simple，rapid and economical，and can be used as the first choice for mutagenicity test.

Key words: Ames test, reverse mutation, HPRT test, gene mutatio, oxidative hair dye