The granular dorsal glands of the giant tree frog Litoria infrafrenata contain five peptides including caerulein (a known neuropeptide), and four new peptides named franatins 1 (MH+ = 1140 Da), 2 (1423), 3 (2180), 4 (2493). The amino acid sequences of the frenatins are detailed: their structures do not correspond to those of peptides isolated from other amphibians or animals. Frenatin 3, Gly-Leu-Met-Ser-Val-Leu -Gly-His-Ala-Val-Gly-Asn-Val-Leu-Gly-Gly-Leu-Phe-Lys-Ser-(OH), has wide spectrum antimicrobial properties.