The human angiotensinogen gene consists of five exons interrupted by four introns and spans 12 kilobases. The gene is expressed in liver and HepG2 cells derived from human hepatoma. To examine whether the angiotensinogen gene is expressed in extrahepatic cells, RNAs from kidney and several human cell lines have been isolated and analyzed by Northern blot hybridization with the cloned gene as a probe. The mRNA for angiotensinogen was detected in human kidney and human glioblastoma (A-172) cells. To investigate the endogenous regulation of angiotensinogen gene expression, HepG2 cells were cultured in the presence of 3-aminobenzamide, a specific inhibitor of poly(ADP-ribose) polymerase. The expression of the angiotensinogen gene was demonstrated to be completely suppressed by 3-aminobenzamide (10 mM).