Endothelin-1 (ET-1) is a peptide implicated in a wide variety of functions involving vascular and non-vascular systems. We have cloned the cDNA encoding the mouse prepro-endothelin-1 (PPET-1) and determined its nucleotide sequence. The putative PPET-1 peptide processing sites are all conserved and the deduced 21-amino-acid mature ET-1 peptide is identical to that of the rat, human, bovine, porcine and rabbit. Using the cloned cDNA as a probe for in situ hybridization, we detected PPET-1 mRNA in different tissues at different stages of mouse embryonic development. Embryos at a stage as early as 9.5 days postcoitum (E9.5) have very strong expression in the branchial epithelium, optic vesicle and the endothelial cells of large blood vessels, including the dorsal aorta and aortic arches. While the expression level in the branchial epithelium was decreasing towards the later stage of embryogenesis, the expression in the endothelial cells increased with age. At E10.5, PPET-1 mRNA was also detected in the otic vesicle as well as in the developing gut epithelium. At later stage of development, the expression of PPET-1 was primarily found in the vascular endothelial cells, cochlea, eye and the gut, with the highest level of PPET-1 mRNA in the endothelial cells of the lung. These data will be useful for analyzing the function of ET-1 in these organs.