Two neuropeptides have been isolated and identi®ed from the secretions of the skin glands of the Stony Creek Frog Litoria lesueuri. The ®rst of these, the known neuropeptide caerulein , is a common constituent of anuran skin secretions, and has the sequence pEQY(SO3 )TGWMDF-NH2 . This neuropeptide is smooth muscle active, an anal-gaesic more potent thanmorphine and is also thought to be a hormone.