Objective To detect the DNA strand breaks induced by adriamycin,potassium chromate or hydrogen peroxide and to study the effect of p tyrosol on DNA oxidative damage in CHL cells.Methods Single cell gel electrophoresis assay(SCGE) was used to detect DNA strand breaks when CHL cells were induced by different concentration of compounds for certain time (adriamycin:1 25h,potassium chromate: 1 75h,hydrogen peroxide:25min);SCGE was used to detect DNA strand breaks and to analyze p tyrosol protection against oxidative damage in CHL cells which were exposed to different concentration of p tyrosol for 1 58h firstly,and then cultured with 0 4mmol/L hydrogen peroxide for 25min.Results Adriamycin,potassium chromate or hydrogen peroxide tested at all concentrations,caused a significant increase in DNA migration measured as tail length and percentage of cells with migrated DNA in exposed CHL cells,and the dose response relationships are apparent between the tail length and the concentration of compound.The pretreatment of p tyrosol (10μg/ml or 20μg/ml) markedly decreased the tail length of CHL cells treated by hydrogen peroxide.Conclusion Adriamycin,potassium chromate and hydrogen peroxide are violent DNA breaking agent.P tyrosol has the ability to inhibit oxidative DNA damage in eukaryote.