Ceruloplasmin (CP) is a copper-binding protein in vertebrate plasma. In the present study, the porcine ceruloplasmin gene was localized to the 13q32-q33 bands by in situ hybridization, using a human CP cDNA probe. This confirmed the localization of the porcine linkage group V to chromosome 13. The CP locus is closely linked to the transferrin locus in pigs. Their relative physical order on chromosome 13 is discussed. Comparisons are made with the order of these two loci in other mammalian species.