The secretions of the parotoid glands of the Australian tree frog Litoria caerulea contain twenty-five peptides of which six, the caeridins, have molecular weights in the 1100-1550 dalton range. We have isolated and characterised twenty-five peptides from the rostral and parotoid gland secretions of Litoria caerulea, including caerulein 1, six different caeridins, and eighteen caerins. This paper describes the primary structures of the six caeridins, and indicates how the exudate's caeridin composition varies with the geographical location of the species.