To investigate the association between neural tube defects and oxidative stress, the levels of several oxidative stress indicators, namely, SOD, MDA, glutathione (GSH) and 8-hydroxy-2-deoxyguanosine (8-OHdG), were measured in the serum, amniotic fluid and urine of women with neural tube-defective fetuses. The gene discussed is SOD1; the disease is isolated spina bifida.