The development of recombinant DNA technology has introduced new directions for the study of the angiotensinogen molecule. The cloning and sequencing of the human and rat cDNAs demonstrate the similarity of angiotensinogen to various serine protease inhibitors produced by the liver and was the beginning of studies looking for new physiological roles of angiotensinogen, in addition to the substrate for renin. The determination of the nucleotide sequence of these cDNAs also allowed the identification of angiotensinogen mRNA in many tissues in addition to the liver that is the major site of synthesis. This multilocalization of angiotensinogen is one of the arguments for the presence and the function of local renin-angiotensin systems. Finally, the hepatic biosynthesis of angiotensinogen is regulated by many different hormonal factors including glucocorticoid, estrogen, thyroid hormone, insulin, and angiotensin II. The cloning of the angiotensinogen gene offers the opportunity to study this regulation at the transcriptional level. We present in this paper a review of the literature concerning the new aspects of angiotensinogen using molecular biological tools and its regulation together with the characterization of the human angiotensinogen gene.