Conserved genome homologies between the chicken and partridge have been demonstrated for chromosomes 1 and Z in previous studies. Morphological differences between the chicken and partridge for chromosome 4 have also been identified. The chicken chromosome 4 is submetacentric while the partridge chromosome 4 is acrocentric. We now report that in spite of this morphological difference, both species share extensive homology for chromosome 4 as determined by fluorescent in situ hybridization (FISH). Since only two chromosomes of the partridge karyotype showed FISH signals, our observation suggests that a chromosome rearrangement (peri- or paracentric inversion) has occurred in the partridge chromosome 4.