Chicken alpha-natriuretic peptide (alpha-chNP) has been identified in chicken heart, which showed higher homology to brain natriuretic peptide (BNP) than to atrial natriuretic peptide (ANP)[1]. Complementary DNA (cDNA) clone encoding a chNP precursor (pre-chNP) was isolated from cardiac cDNA library and sequenced. Pre-chNP was 140-residue peptide carrying a 24-residue signal peptide at the N-terminus and alpha-chNP at the C-terminus, and did not exhibit high homology to porcine BNP except for the C-terminal region. However, a characteristic AT-rich nucleotide sequence commonly found in mammalian BNPs was also present in the 3'-untranslated reigon. Thus, chNP is concluded to be concluded to be classified into the BNP-type.