The mouse Myxovirus resistance protein 1 (Mx1) is known to be sufficient to confer resistance to influenza viruses, and genes encoding Myxovirus resistance protein 1 (Mx1) is, therefore, an interesting candidate gene for disease resistance in farm animals. The porcine Mxl gene has already been identified and characterized based on its homology with mouse Mxl; the full-length coding region of the pig Mxl gene spans 2 545 bp (M65087) and is organized into 17 exons compared with the human ortholog mRNA. In this study, the exons 9, 10, 11 and introns 6, 9 of the porcine Mxl gene were cloned and sequenced; two SNPs were identified in exons 9, 10, 11 but none of the SNPs led to an amino acid exchange, and the other eleven variants were detected in introns 6 and 9, respectively. Differences in allele frequency among Meishan, Large White, Tibetan, Tongcheng, Huainan, and Duroc pigs were observed within intron 9, of which an A → G substitution at position 186 was detected as an Msp Ⅰ PCR-restriction fragment length polymorphism (PCR-RFLP). The association analysis using the Large White×Meishan F2 offspring suggested that the Mxl genotype was associated with variation in several immunity traits that are of interest in pig breeding. However, further investigations in more populations are needed to confirm the above concept.