Various peptide fragments related to eglin c, which consists of 70 amino acid residues, were synthesized by a conventional solution method and their inhibitory effects on leukocyte elastase, cathepsin G and α-chymotrypsin were examined. Among them, H-Arg-Glu-Tyr-Phe-OMe (eglin c 22-25) and H-Ser-Pro-Val-Thr-Leu-Asp-Leu-Arg-Tyr-OMe (eglin c 41-49) inhibited cathepsin G and α-chymotrypsin but not leukocyte elastase, while H-Thr-Asn-Val-Val-OMe (eglin c 60-63) inhibited leukocyte elastase but not cathepsin G or α-chymotrypsin, although eglin c potently inhibited leukocyte elastase, cathepsin G and α-chymotrypsin. These results indicated that the interaction sites of eglin c with leukocyte elastase, cathepsin G and α-chymotrypsin might be different.