Endothelial PAS domain protein 1 (EPAS1), also called hypoxia-inducible factor-2, is a key regulatory factor of hypoxic responses and plays an essential role in high-altitude adaptation in mammalian species. In this study, polymorphisms of EPAS1 were detected in 217 individuals from 2 Tibetan pig populations and 3 low-altitude pig breeds by DNA pooling, PCR-SSCP, PCR-RFLP and DNA sequencing methods. A total of 14 synonymous polymorphisms were identiifed in the coding region. The analysis suggested that SNP1 (G963A), SNP7 (C1632T), SNP10 (G1929A) and SNP11 (G1947A) showed potential association with high-altitude environment because of their particular variation patterns in Tibetan pigs. Linkage disequilibrium (LD) of these SNPs was analyzed. One common LD block including 5 SNPs clustering in exon 12 was identiifed in all studied pig populations. Haplotype H1 (AGGTC) in LD block was dominant in Tibetan pigs (76.6 and 74.2% in Linzhi (LZ) and Chayu (CY) pigs, respectively) and segregated at higher frequency than that in low-altitude pig breeds (52.3, 58.7 and 56.2% in Wuzhishan (WZS), Min (M) and Laiwu (LW) pigs, respectively), indicating that H1 may relate to adaptation to high altitude in Tibetan pigs. These ifndings raise hope thatEPAS1gene can be a candidate gene that involved in adaptation of high altitude in Tibetan pigs.