A new human leukocyte elastase inhibitor called the guamerin was isolated and purified from Korean native leech, Hirudo nipponia in our laboratory. For cloning of guamerin, total RNA and mRNA were isolated from leech body. And then first-strand cDNA, we designed two degenerate primers that were made from N-terminal and C-terminal amino acid sequences of guamerin. We isolated PCR product of 170bp size and cloned 170bp PCR product into SmaI site of pUC19. And then the sequence of the insert was determined by dideoxy method with universal primer and reverse primer. The sequences of PCR products were completely determined and product showed the structural gene of guamerin. Guamerin fusion protein expression and cDNA library construction are carried out.