Combinations of four alpha-2-globulin allotypes were studied for their distribution in pigs of nine different breeds and hybrid groups. Based on this analysis, a new, previously unpublished polyallelic genetic system designated A2G was postulated. The complex alleles of this system control alpha-2-globulin allotypes and are suggested to be encoded by genes of two subloci. One of these subloci is virtually monomorphic, whereas the other has at least four allelic variants.