A family of bombinin-related peptides is present in the skin of Bombina variegata. These peptides contain 27 residues with Gly as N-terminus and display antimicrobial activity. From sequence analysis of the cDNAs encoding for the corresponding peptide precursors, the presence of a novel 20-residue peptide with Ile as N-terminus was predicted. We have now purified a family of hydrophobic peptides named H1-H5, whose sequences correspond to the predicted peptide with some variability in positions 1, 2 and 8. In particular, H3-H5 contain a D-alloisoleucine residue in the second position. All these peptides display antibacterial and haemolytic activity.