Defects in mitochondrial function have been shown to participate in the induction of neuronal cell injury. The present study assessed the preventive effect of a prostaglandin E(1) analogue misoprostol against the toxicity of parkinsonian neurotoxin 1-methyl-4-phenylpyridinium (MPP(+)) with respect to the mitochondria-mediated cell death process and oxidative stress. MPP(+) induced the nuclear damage, the changes in the mitochondrial membrane permeability, the formation of reactive oxygen species and the depletion of GSH, which leads to cell death in differentiated PC12 cells. Misoprostol prevented the toxic effect of MPP(+). Treatment with misoprostol significantly attenuated the MPP(+)-induced mitochondrial membrane permeability change that leads to the increase in pro-apoptotic Bax and Cytochrome c levels, and subsequent caspase-3 activation. The protective effect of misoprostol may be supported by the inhibitory effect of prostaglandin E(1) on the MPP(+) toxicity. Misoprostol significantly attenuated another parkinsonian neurotoxin rotenone-induced cell death. The results show that misoprostol may prevent the MPP(+) toxicity by suppressing the mitochondrial membrane permeability change that leads to the Cytochrome c release and caspase-3 activation. The preventive effect seems to be ascribed to the inhibitory effect on the formation of reactive oxygen species and depletion of GSH.