Pregnancy-specific beta 1-glycoprotein (PSG) transcripts have been identified in a number of placental and non-placental tissues. Using a placental PSG cDNA probe to screen a normal human intestinal cDNA library we have isolated 22 hybridizing clones. These clones could be divided into four groups. Nucleotide sequence analysis showed that one group of clones correspond to functional and another group correspond to non-functional PSG cDNAs. The other two groups are homologous to the nonspecific cross-reacting antigen (NCA) and biliary glycoprotein (BGP), both of which are members of the carcinoembryonic antigen (CEA) family. Thus, PSG, NCA and BGP are co-expressed in normal human intestine. RNA and immunoblot analysis, along with polymerase chain reaction amplification further confirm the expression of PSG in human intestinal tissue.