The GST Fpi and GST Ppi, pi class glutathione S-transferase (GST), were purified from human fetal livers and placentas, respectively. Both GST enzymes were indistinguishable each other in their subunit molecular weights, immunochemical properties and substrate specificities. Three clones (pFGP-1, pFGP-2 and pFGP-3) coding for the pi class GST purified from fetal livers were isolated from a human fetal liver cDNA library. The full-length clone encodes a polypeptide comprising 210 amino acid including the initiator methionine. All of these cDNA clones were nearly identical to a human placental cDNA clone, pGpi 2. The pFGP-1 cDNA had only a single base transition accompanied by an amino acid transition in the coding region, at position 313. The pFGP-2 and pFGP-3 cDNAs were also nearly identical to pGpi 2 cDNA, having only a single silent C-->T transition in the coding region, at position 555.