We have shown previously that the sequence of olive flounder (Paralichthys olivaceus) hsp70-related cDAN has a high similarity with those of cognate hsc70 of other species (Kim et al., 1999; J. Aquaculture, 12:91-100). In order to investigate whether this gene encodes the congate hsc70, we examined the expression of this gene in normal and heat-shocked conditions. By in vitro translation, this gene encoded a 70 kD protein which was constitutively experessed and was not induced by heat shock. This translated protein was recognized by anti-hsp/hsc70 antibody. Tests of heat-inducibility showed that this gene was constitutively expressed in normal conditions and its expression was not increased after heat shock. The expression levels of this gene were high in stomach, gill, intestine, kidney and brain, moderate in liver, and comparatively low in overy and heart. Furthermore, Northern blot analysis of transcript expression showed that the corresponding mRNA were detected throughout embryonic development in the absence of any heat shock. These results provided evidence that olive flounder hsp70-related cDNA encoded to cognate member of hsp70 family, hsc70.