Ginkgo biliba has been used for bronchitis and asthma in oriental countries and its leaf extract(GBE) contains 24% ginkgoflavone glycoside and 6% terpenoid. Flavonoids and terpenoids are known to have various antioxidant effects such as scavenging of free radicals and chelation of transtional metals. Antioxidant effect of GBE against 1,2,4-benzenetriol(BT), one of toxic metabolites of benzene, was demonstrated throughbsister chromatid exchange(SCE) analysis, single cell gel electrophoresis(SCGE) analysis, DNA cleavage assay and lipid peroxidation production analysis. The means of SCE frequencies at 10, 25 and 50$mu$M concentration of BT were 7.72, 8.02, 9.22 respectively. In addition of GBE with concentration of 50, 200 and 500$mu extrm{g}$/$mell$, SCE frequencies were decreased significantly.(p<0.05) According to SCGE analysis, BT induced DNA damage in a dose-dependent manner at concentration of 10 and 50 $mu$m and the DNA damage induced by BT was significantly protected by GBE(p<0.001). No genotoxicity was observed by GBE treatment alone on DNA cleavage. The effect of BT on lipid peroxidation product, Malondiadehyde(MDA), was increased with concentration of BT(10 and 50 $mu$M) and reduction in MDA was noted when GBE was added. From above results it is suggested that GBE could protect the cell and DNA from pro-oxidant effect by reactive oxigen species induced by BT.