Bombesin and its receptors have been demonstrated to be involved in a larger array of physiological and pathophysiological conditions including memory and fear behavior, lung development and injury, and tumor growth. A bombesin-like peptide named bombesin-RS was purified and characterized from the skin secretions of the frog, Rana shuchinae. Its amino acid sequence (pETSFMAPSWALGHLM-NH2) was determined by auto Edman degradation and mass spectrometry. The cDNA encoding bombesin-RS precursor was cloned from skin cDNA library of this frog. The precursor is composed of 67 amino acid residues including a copy of mature bombesin-RS. Two predicted enzymatic processing sites (-Lys-Lys- and -Lys-Arg-) are flanked at the mature bombesin-RS sequence. In the in vitro myotropic contraction experiment, the synthesized bombesin-RS displayed stimulating effect toward rat stomach strips, suggesting that bombesin-RS acts as agonist as most other bombesin-related peptides do.