Gastrin and cholecystokinin exert a variety of physiological actions in the central nervous system and digestive tract that are mediated through one or more receptors exhibiting similar affinity for the two peptides. We isolated genomic clones encoding the rabbit gastrin/CCKB receptor by screening a rabbit EMBL phage library with a cDNA probe based on the nucleotide sequence of the human gastrin/CCKB receptor. The gene contained a putative 1356-bp open reading frame consisting of five exons interrupted by 4 introns and encoded a protein of 452 amino acids. The putative protein-coding region of the gene exhibits 93 to 97% amino acid similarity with corresponding cDNAs previously identified in human, canine and rodent brain or gastric tissues.