Receptors for cholcystokinin (CCK) can be pharmacologically classified into at least two distinct subtypes, CCKAR and CCKBR. In an effort to determine whether the CCKA and CCKB receptors may be associated with certain CNS or gastrointestinal diseases, we have localized and compared the human and mouse chromosomal loci encoded by the CCKAR and CCKBR genes. The gene encoding the CCKA receptor maps to a syntenic region of human chromosome 4 and mouse chromosome 5. The CCKB receptor gene, on the other hand, resides on a syntenic region of human chromosome 11 and distal mouse chromosome 7. Localization of the CCK receptors with two dopamine receptors, DRD5 (4p15.1-p15.3) and DRD4 (11p15), provides the interesting possibility of coinvolvement in neuropsychiatric or CNS illnesses.