Angiotensinogen is the precursor of biologically active peptide angiotensin II and its synthesis is increased in the liver during acute inflammation. We have used radiolabeled human angiotensinogen cDNA to study the effect of hepatocyte stimulating factor (HSF), a protein synthesized in differentiating monocytes which increases the synthesis of various hepatic proteins during inflammation, on angiotensinogen mRNA levels in human hepatoma cells (HepG2). Our results indicate that angiotensinogen mRNA is present in human hepatoma (HepG2) cells and its levels are decreased when treated with hepatocyte stimulating factor. Although dexamethasone elevated angiotensinogen mRNA levels, HSF reduced this increase. These results suggest that a factor other than HSF may be involved in elevating the angiotensinogen mRNA levels in the liver during inflammation.