Oxidative damage to the genome can yield the base 8-oxo-7,8-dihydroguanine (OG). In vitro studies suggested OG would preferentially form in 5'-GG-3' sequence contexts after exposure to reactive oxygen species. Herein, OG locations in the genome were studied by development of "OG-Seq" to sequence OG sites via next-generation sequencing at similar to 0.15-kb resolution. The results of this study found similar to 10 000 regions of OG enrichment in WT mouse embryonic fibroblasts and similar to 18 000 regions when the OG repair glycosylase Oggl was knocked out. Gene promoters and UTRs harbor more OG-enriched sites than expected if the sites were randomly distributed throughout the genome and correlate with reactive 5'-GG-3' sequences, a result supporting decades of in vitro studies. Sequencing of OG paves the way to address chemical and biological questions surrounding this modified DNA base, such as its role in disease-specific mutations and its epigenetic potential in gene regulation.