A polymerase chain reaction (PCR) primer set for a chicken pkci gene on the Z-chromosome, chPKCI, amplified a 329 bp fragment of genomic DNA in chickens but not quail. Likewise, a PCR primer set for the quail pkci gene on the Z-chromosome, quPKCI, amplified a 95 bp fragment of genomic DNA in quail but not chickens. These chicken and quail primers validly identified chicken-quail hybrids derived from Z-chromosome carrying sperm of chicken and the hybrid derived from Z-chromosome carrying oocyte of quail, respectively.