A liver-specific antigen previously demonstrated in saline extracts of human liver has been purified by consecutive ammonium sulfate precipitation, ion-exchange chromatography and gel filtration. The purified antigen migrated as a single bank in gel electrophoresis. This antigen has a mol. wt of 44,000 daltons. Amino acid analysis showed the acidic amino acids to outnumber the basic amino acids while glycine is the most abundant neutral amino acid. No carbohydrate could be demonstrated in the purified preparation of this antigen. © 1977.