In this case-control study, we evaluate the rs3764435 polymorphism of ALDH1A1. The SNP rs3764435 is an intronic variant reported to be a member of a haplotype that may regulate the expression of ALDH1A1. Our results showed that the C allele is present more frequently in non-PD subjects (p = 0.021) and logistic regression revealed that the C/C genotype might be acting as a protective factor that decreases the risk of PD in Mexican mestizos. This evidence concerns the gene ALDH1A1 and Parkinson disease.