Objectives and Methods : To evaluate the mechanism of oxidative damage by xanthine oxydase(XO) and hypoxanthine(HX)-induced oxygen radicals, MTT assay and NR assay were carried out after the cultured mouse spinal sensory neurons were preincubated for 4 hours with various concentrations of XO/HX. And the amount of total protein. neurofilament EIA. lipid peroxidation and LDH activity were measured, to evaluate the protective effect of Herbar Chelidonii(HC) water extract on cultured spinal sensory neurons damaged by XO/HX. after the cultured mouse spinal sensory neurons were preincubated with various concentrations of HC water extract for 3 hours prior to exposure of XO/HX. Results : XO/HX decreased significantly the survival rate of the cultured mouse sensory neurons by NR assay and MTT assay In proportion to concentration and exposed time. In proportion to concentration and exposed time on cultured spinal sensory neurons, XO/HX showed the quantitative decrease of neurofilament by EIA. the decrease of total protein amount by SRB assay and the Increase of lipid peroxidation as well as LDH. HC showed the quantitative increase of neurofilament and total protein, but showed the decrease of lipid peroxidation and LDH activity against the neurotoxicity of XO/HX. Conclusions : From the above results, it is concluded that XO/HX have a neurotoxic effect on cultured spinal sensory neurons and that the herbs extract, such as HC, prevent the toxicity of XO/HX effectively in that they decrease lipid peroxidation and LDH activity.