A 340 bp DNA fragment was amplified from barnacle (Megabalanus volcano) cDNA by polymerase chain reaction using primers designed based on the amino acid sequences of barnacle cadmiuminducible peptides CdIP1 and CdIP2. The whole sequence was determined by rapid amplification of cDNA ends method. The cDNA contained an open reading frame encoding 71 amino acid residues and the sequences for CdIP1 and CdIP2 were found to be located in the center of this coding region. Although CdIP1 and CdIP2 had been detected only in the cadmium-exposed barnacles, their mRNA was present both in cadmium-exposed barnacles and in unexposed barnacles. These results suggest that posttranslational proteolytic processing may be induced in the presence of cadmium.