Abstract: The Paraoxonase 1 gene (PON1) encodes paraoxonase which hydrolyzes organophosphate pesticides and nerve gasses. In addition, PON1 has been shown to have significant antiatherosclerotic effects and is a major candidate gene associated with the reduction of atherosclerosis. Most of the literature reporting polymorphisms in PON1 has been in humans while less information about the polymorphism of PON1 gene has been reported in mammals, especially in bovine species. Polymorphisms in the PON1 gene were evaluated in Simmental x Chinese Yellow cattle (n = 32) and Longdong cattle (n = 37) using PCR-SSCP in exons 1-9 of the PON1 gene. Results demonstrated polymorphisms in the bovine PON1 gene at exons 4, 6, 8 and 9. DNA sequencing identified specific substitutions in exon 4, 6, 8 and 9 (g.338G>A, g.647C>T, g.896C>T and g.998T>C, respectively). Two genotypes were identified in exon 4 (GG and AG), exon 6 (TT and CT) and exon 9 (TT and CT) while 3 genotypes were identified in exon 8 (CC, CT and TT). The allelic frequency for the G allele was 92.03% and the A allele was 7.97% in exon 4. Allelic frequencies for the T and C alleles were 89.86 and 10.14%, respectively, in exon 6. In exon 8, frequencies for the C and T alleles were 94.93 and 5.07%, respectively. In exon 9, allelic frequencies for the T and C alleles were 88.41 and 11.59%, respectively.