To research effects of the artificial selection of <i>Gallus gallus</i> on <i>G. domesticus</i>' nucleotide diversity of immune genes, sequence polymorphisms of <i>G. domesticus</i> (23 genes), <i>G. gallus</i> (23 genes), <i>G. lafayetti</i> (17 genes), and <i>G. sonneratii</i> (17 genes) were obtained from GenBank. The data set included 819 polymorphisms. Immune gene polymorphism and selection efficiency in the data from those four species of <i>Gallus</i> were calculated. By calculating the q<sub>w</sub> (Watterson's estimator) of each site, an average q<sub>w</sub> for each species and the minimum number of re-combinations in each species and by estimating the selection efficiency for <i>G. domesticus</i> and <i>G. gallus</i>, neither significant nucleotide diversity nor genetic-diversity-q<sub>w</sub>- difference was found between <i>G. domesticus</i> and <i>G. gallus</i>. The results indicated that the patterns of genetic diversity in <i>G. domesticus</i> were strongly influenced by recombination and, because Tajima's D has a negative value, recombination was the main mechanism responsible for the immune gene evolution of <i>G. gallus</i>.