Abstract: Objective To study effects of octachlorodipropyl ether on DNA synthesis in CHL in vitro.Methods Fluorimetric quantification assay was applied to detect DNA synthesis of CHL cells treated with differ ent concentrations(0.250,0.187,0.125,0.062,0.046,0.031 Lg/ml).Results In the concentration gruop of 0.062 and 0.046 μg/ml,DNA synthesis quantities were significantly different from the control group(P<0.05),However,DNA synthesis inhibition and good dose-response relationships were shown in the gruop of 0.250,0.187 and 0.125μg/ml.DN A synthesis quantities of 0.250 μg/ml group indicated continual descent trend when it was treated without octachlorodipropyl ether in 2~12 horus.Conclusion Low concentration of octachlorodipropyl ether could lead to the increase of DNA synthesis ability in CHL cells.Concentrations of 0.250,0.187,and 0.125 Lg/ml may lead to DNA synthesis inhibition,which was caused by DNA damage.