Most amphibians belonging to Rhacophoridae have an arboreal life. A large amount of bioactive peptides have been identified from amphibian skin, but none from amphibians belonging to Rhacophoridae have been reported to date. A tachykinin-like peptide, tachykinin-Thel, was purified and characterized from skin secretions of the tree frog, Theloderma kwangsiensis. Its primary structure was determined as KPSPDRFYGLM-NH2 by Edman degradation and mass spectrometry analysis. cDNA sequence encoding the precursor of tachykinin-Thel was cloned from the skin cDNA library. Tachykinin-Thel induced the contraction of isolated ileum smooth muscle in a dose-dependent manner. The current work reported a bioactive peptide, tachykinin-Thel, from Rhacophoridae amphibians and confirmed the presence of tachykinin-like peptide in the skin of the tree frog, which may facilitate their arboreal life.