A human 8-oxoguanine-DNA glycosylase (hOGG1) is the main enzyme that repairs 8-oxoG, which is a critical mutagenic lesion. There is a great deal of interest in the up- or down-regulation of OGG1 expression after DNA damage. In this study, we investigated the effect of a DNA-alkylating agent, methylmethane sulfonate (MMS), on hOGG1 expression level and found that MMS treatment resulted in an increase in the functional hOGG1 expression in HCT116 cells. A region between -121 and -61 of the hOGG1 promoter was found to be crucial for this induction by MMS. Site-directed mutations of the two inverted CCAAT motifs substantially abrogated the induction of the hOGG1 promoter as a result of MMS treatment. In addition, the NF-YA protein (binding to the inverted CCAAT box) was induced after exposing cells to MMS. Moreover, gel shift and supershift analyses with the nuclear extracts prepared from HCT116 cells identified NF-YA as the transcription factor interacting with the inverted CCAAT box. Mutations of the inverted CCAAT box either prevented the binding of this factor or abolished its activation as a result of MMS treatment. Finally, this study showed that hOGG1-expressing HCT116 cells exhibited increased hOGG1 repair activity and resistance to MMS. Overall, these results demonstrate that MMS can up-regulate hOGG1 expression through the induction of the transcription factor, NF-YA, and increased transcription level of the hOGG1 gene correlates with an increase in enzyme activity providing functional protection from MMS.