The polymerase chain reaction (PCR) has been combined with hybrid somatic cell technology to extend the bovine physical map. Eight bovine loci--glycoprotein hormone alpha (CGA), coagulation factor X (F10), chromogranin A (CHGA), low-density lipoprotein receptor (LDLR), human prochymosin pseudogene (CYM), oxytocin (OXT), arginine-vasopressin (ARVP), and cytochrome oxidase c subunit IV pseudogene (COXP)--were assigned to bovine syntenic groups with this approach. CGA was assigned to bovine syntenic group U2, F10 to U27, CHGA to U4 [bovine Chromosome (Chr) 21], LDLR to U22, CYM to U6, OXT and ARVP to U11, and COXP to U3 (bovine Chr 5). Seven of these genes, CGA, F10, CHGA, LDLR, OXT, ARVP, and CYM, further delineate regions of chromosomal conservation on human Chrs 6, 13, 14, 19, 20, 20, and 1, respectively. CHGA, OXT, and ARVP are unmapped in the mouse. Comparative mapping predicts the mouse CHGA will map to Chr 12, and mouse OXT and ARVP will map to mouse Chr 2. Furthermore, human CYM is predicted to be sublocalized to 1p32-q21. The primers developed for these eight loci will be useful for the development of hybrid somatic cell panels in the future as well as establishing a collection of bovine expressed sequence tags.