The neuroprotective effects of protocatechuic acid (PCA), a phenolic compound isolated from the kernels of Alpinia oxyphylla, on hydrogen peroxide (H₂O₂)-induced apoptosis and oxidative stress in cultured PC12 cells were investigated. Exposure of PC12 cells to 0.4�mM H₂O₂ induced a leakage of lactate dehydrogenase (LDH) and decreased cell viability denoted by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. PCA increased PC12 cellular viability and markedly attenuated H₂O₂-induced apoptotic cell death in a dose-dependent manner. By flow cytometric analysis, PCA showed its significant effect on protecting PC12 cells against H₂O₂-induced apoptosis. In these cells, the levels of glutathione (GSH) and activity of catalase were augmented, while glutathione peroxidase activity remained unchanged. In addition, PCA also protected against cell damage induced by H₂O₂ and Fe²⁺, which generated hydroxyl radicals (˙OH) by the Fenton reaction. These results suggest that PCA may be a candidate chemical for the treatment of oxidative stress-induced neurodegenerative disease.