A 19 kDa protein was identified in specific granules of human neutrophils. A full-length cDNA clone was isolated from a human CML cDNA library, based on amino-acid sequences of isolated tryptic fragments. This clone includes the recently identified cDNA for FALL-39/CAP-18. Aminoacid sequences of proteolytic fragments derived both from the conserved N-terminal cathelin-like region and the highly variable C-terminal region characteristic of this family of bactericidal, LPS binding proteins, were in complete agreement with the sequence deduced from the cDNA. Thus, the 19 kDa protein is hCAP-18, stored as a 'pro-peptide' in specific granules.