Lactase gene expression declines with aging (lactase non-persistence) in the majority of humans worldwide. Lactase persistence is a heritable autosomal dominant condition and has been strongly correlated with several single nucleotide polymorphisms (SNPs) located ~14-kb upstream (-13907, -13910 and -13915) of the lactase gene in different ethnic populations. In contrast to the -13907*G and -13910*T SNPs, the -13915*G SNP was previously believed not to interact with Oct-1. In the present study, however, Oct-1 is shown to interact with the -13915*G SNP region DNA sequence by EMSAs and gel supershift. In addition, Oct-1 is capable of enhancing promoter activity of a lactase promoter-reporter construct harboring the 13915*G SNP sequence in cell culture. Oct-1 binding to the -13907 to -13915 SNP region therefore remains a candidate interaction involved in lactase persistence.