A genetic polymorphism of the pig amylase 2 system is described. It is controlled by two codominant genes, Am 2A and Am 2B. A comparison of some breeds from Byelorussian breeding farms gives the following frequencies for the alleles Am 2A and Am 2B, respectively: 0.35 and 0.865 in Large White (n = 682), 0.257 and 0.743 in Byelorussian Black and White (n = 400), 0.540 and 0.460 in Hampshire (n = 51). While studying the genotype distribution according to the Hardy-Weinberg law, a genetic imbalance in Byelorussian Black and White pigs was established (chi2 = 56.4). Genetic relationship between the Am 1 and Am 2 loci was not found.