Abstract : Activity‐dependent neurotrophic factor (ADNF) is produced by astrocytes in response to neuronal depolarization and, in turn, promotes neuronal survival. A nineamino acid ADNF peptide (ADNF9) exhibits full neurotrophic activity and potently protects cultured embryonic rat hippocampal neurons from oxidative injury and apoptosis. Picomolar concentrations of ADNF9 induced an increase in nuclear factor‐κB (NF‐κB) DNA‐binding activity within 1 h of exposure, with a maximum increase of ~10‐fold by 6 h. Activation of NF‐κB was correlated with increased resistance of neurons to apoptosis induced by exposure to Fe²⁺. The antiapoptotic action of ADNF9 was abolished when NF‐κB activation was specifically blocked with κB decoy DNA. Oxidative stress was attenuated in neurons pretreated with ADNF9, and this effect of ADNF9 was blocked by κB decoy DNA, suggesting that ADNF9 suppresses apoptosis by reducing oxidative stress. ADNF9 also prevented neuronal apoptosis following trophic factor withdrawal via an NF‐κB‐mediated mechanism. Thus, NF‐κB mediates the neuron survival‐promoting effects of ADNF9 in experimental models relevant to developmental neuronal death and neurodegenerative disorders.