Octopus vulgaris,which owns a number of unique stress protection mechanisms is considered to be the most intelligent species of all invertebrates.A 2 709 bp fulllength cDNA sequence of heat shock protein 90(HSP90) gene from O.vulgaris was obtained by homologous amplification and rapid amplification of cDNA ends(RACE).It consisted of a 119 bp 5′untranslated region(UTR),a 2 136 bp open reading frame(ORF)and a 454 bp 3′UTR.The inferred amino acids sequence was composed of 711 amino acids,whose molecular weight and isoelectric point were 81.5 ku and 5.09,respectively.Homologous analysis showed the inferred amino acids sequence was highly conserved and contained five classicalHSP90 signature sequences.Realtime quantitative PCR(RT-PCR)results displayedHSP90 expressed in every tissues chosen,with the most in liver.This study which was the first time to obtainHSP90 gene from Cephalopod played an important role in studying stress mechanisms on the most intelligent invertebrate.