AIM: To examine the effects of the APP17-mer peptide against 2Aβ25-35-induced apoptosis and gain some insight into the neuroprotective mechanism of the APP17-mer peptide. METHODS: Protective effects of APP17-mer peptide against Aβ25-35- induced apoptosis in SH-SY5Y cell was proved by cell morphology, LM-PCR DNA ladder assay and FCM assay. The antiapoptotic mechanism of APP17-mer peptide was investigated using the MTT assay to measure mitochondrial energy redox state, using the fluorescent probe DCF-DA, Rhodamine 123 to measure relative levels of cellular peroxides and mitochondrial membrane potential and using Western blot for AIF and NF-kB to detect the expression of AIF and NF-KB. RESULTS: Damage of cell morphology was ameliorated by pretreating with APP17-mer peptide. The apoptotic rate of the SH-SY5Y cells exposed to Aβ25-35 in the presence of APP17-mer peptide decreased from 63.75% to 28.25%. Exposure of SH-SY5Y to Aβ25-35 for 48 h resulted in an increase in DCF-DA fluorescence, a decrease in Rhodamine 123 fluorescence and MTT reduction, the results were weakened by pre-incubating with APP17-me.r peptide for 30 minutes. Treatment of cells with APP17-mer peptide resulted in a significant attenuation in the expression of AIF and a strong increase in the expression of NF-KB. CONCLUSION: APP17-mer is protective against cell apoptosis induced by Aβ25-35 by provoking and sustaining upregulation of a key antiapoptotic transcription factor NF-KB, by suppressing oxyradical production and by preserving mitochondrial function and inhibiting the release of apoptotic protein from mitochondria.