Human angiotensinogen cDNA clone was isolated from a liver cDNA library using a 32-nucleotide-long, synthetic oligonucleotide The cDNA insert was 1,030 bp long and coded for the secretory and biologically active angiotensin II regions of the angiotensinogen molecule The RNA from rat liver, brain, and heart was analyzed by the Northern hybridization procedure using nick translated angiotensinogen cDNA as a probe In addition to liver, the angiotensinogen mRNA is present in the brain and the heart The angiotensinogen mRNA in the heart is at least fourfold to fivefold more abundant as compared with the liver We also provide evidence that angiotensinogen mRNA is present in the rat atria and right ventricle but not detectable in the left ventricle The size of the angiotensinogen mRNA is the same from all three of the tissues, as judged by their electrophoretic mobilities