The reactive oxygen species and Ca2+ overload play a critical role in ischemia/reperfusion (I/R) injury. MCI-186 has potent effects in the brain as a free radical scavenger in ischemia-reperfusion. Acute glucose-oxygen deprivation and subsequent reoxygenation were used to model ischemia/reperfusion injury in cultured hippocampal cells. MCI-186 reduced malondialdehyde level and raised the SOD activity when applied upon reoxygenation in a dose-dependent manner compared with the untreated group. The peak neuroprotective effects occurred at 100 and 300 microM. Intracellular free calcium concentration ([Ca2+]i) was significantly reduced in the 100 microM MCI-186-treated group compared to the untreated group (32.5+/-4.0 versus 50.2+/-3.6, p<0.01). Treatment with 100 microM MCI-186 significantly inhibited the decrease of mitochondria membrane potential after simulated ischemia/reperfusion (204+/-11.6% compared with the untreated group, p<0.01). Cell apoptotic rate was significantly decreased following MCI-186 treatment from 33.7+/-2.3% (untreated group) to 16.6+/-1.4% (100 microM MCI-186 treated group). There was no significantly protective difference between 100 and 300 microM MCI-186. MCI-186 effectively protects neuron injury after simulated ischemia/reperfusion by inhibiting lipid peroxidation, reducing Ca2+ overload, elevating mitochondria membrane potential, and decreasing apoptosis.