This paper reviews the present state of the studies on the repair of a major oxydative lesion on DNA, the 8-oxo-guanine (8-OxoG). This modified base has been proved to be highly mutagenic and therefore implicated in the ethiology of several pathologies. The cloning of the yeast OGG1 gene, a functional homolog of the fpg from bacteria, allowed the isolation of the mammalian homologs. These genes code for 8-OxoG DNA glycosylases/lyases, whose biochemical properties are consistent with their postulated role as the main defence against the genetic instability induced by the presence of 8-OxoG in DNA. This, together with the mutator phenotype of the yeast ogg1 mutant strains, make of the human OGG1 a candidate for a cancer predisposition gene. The localization of this gene to chromosome 3p and other evidences discussed in this paper indicate that OGG1 could be a tumor suppressor gene implicated in lung cancer.