Di-n-butyl phthalate (DBP) was used in the plastic industry and widely distributed in the environment, which might cause adverse effects to living organisms. Previously, it had been shown that DBP produced reproductive, developmental toxicity and liver enlargement in rodents, and the mechanisms behind this could involve oxidative injury. To study the effects of DBP on the acute oxidative damage, the liver cells of Wistar rats were exposed to different concentration of DBP (0, 5, 20 and 80 mu mol.L-1) for one hour in vitro, then Nitro blue tetrazolium (NBT)-illumination method, Thiobarbituric acid (TBA) assay and KCl-SDS assay were used to measure the change of the activities of surperoxide dismutase (SOD), the contents of malondialdehyde (MDA) and the coefficient of DNA-protein crosslinks (DPC) respectively. With the increase of DBP concentrations, statistical significant decrease of the SOD activities, increase of MDA contents and DPC coefficient were observed. These results suggested that DBP could induce the acute oxidative damage in liver cells of rat.