The full-length cDNA of insulin-like growth factor binding protein 1 gene(IGFBP-1) was obtained from the liver of Japanese flounder(Paralichthys olivaceus)using RACE method. The complete cDNA of P.olivaceus IGFBP-1 is 1 070 bp and its ORF includes 729 bp encoding 242 amino acid residues.The IGFBP-1 was highly homologous with IGFBP-1 gene in fish through phylogency analysis. The nucleotide sequence of IGFBP-1 from P.olivaceusshared 95% homology with that of Scophthalmus maximu,and the deduced amino acid analysis showed that the sequence similarities betweenP.olivaceusand S.maximu,Seriola quinqueradiata,Perca flavescens,Salvelinus alpines,Cyprinus carpio andDanio rerio,are 89%,89%,84%,79%,67% and 67%,respectively. Semi-quantitative RT-PCR results demonstrated that IGFBP-1 mRNA was detected in unfertilized egg,fertilized egg,embryonic and larval development,and various adult tissues.Moreover,real-time quantitative RT-PCR results showed that IGFBP-1 gene had the highest expression in adult liver and was expressed in a stage-specific manner during embryonic and larval development.