The tumor suppressor protein p53 is essential for neuronal death in several experimental settings and may participate in human neurodegenerative disorders. Based upon recent studies characterizing chemical inhibitors of p53 in preclinical studies in the cancer therapy field, we synthesized the compound pifithrin-alpha and evaluated its potential neuroprotective properties in experimental models relevant to the pathogenesis of stroke and neurodegenerative disorders. Pifithrin-alpha protected neurons against apoptosis induced by DNA-damaging agents, amyloid beta-peptide and glutamate. Protection by pifithrin-alpha was correlated with decreased p53 DNA-binding activity, decreased expression of the p53 target gene BAX and suppression of mitochondrial dysfunction and caspase activation. Mice given pifithrin-alpha exhibited increased resistance of cortical and striatal neurons to focal ischemic injury and of hippocampal neurons to excitotoxic damage. These preclinical studies demonstrate the efficacy of a p53 inhibitor in models of stroke and neurodegenerative disorders, and suggest that drugs that inhibit p53 may reduce the extent of brain damage in related human neurodegenerative conditions.