AbstractArsenic is a major public health concern world-wide. While it is an established carcinogen and associated with a number of other adverse health outcomes, the mo-lecular mechanisms underlying arsenic toxicity are not completely clarified. There is mounting evidence from human studies suggesting that arsenic exposure is associ-ated with epigenetic alterations, including DNA methyla-tion. In this review, we summarize several recent human studies that have evaluated arsenic exposure using the Illumina HumanMethylation 450K BeadChip, which in-terrogates more than 485,000 methylation sites across the genome. Many of these studies have observed novel regions of the genome associated with arsenic exposure. However, few studies have evaluated the biological and functional relevance of these DNA methylation changes, which are still needed. We emphasize the need for future studies to replicate the identified DNA methylation sig-nals as well as assess whether these markers are associat-ed with risk of arsenic-related diseases