The damaged DNA base 8-oxo-2'-deoxyguanosine (OdG), which is produced by reactive oxygen species, is highly mutagenic and has been linked to diseases such as rheumatoid arthritis, lupus, and cancer. Upon replication, OdG can pair with dA rather than dC, leading to dG to T transversion mutations. We worked with MutY, a bacterial repair glycosylase, that removes the adenine from OdG:dA mismatches, there by protecting DNA from these transversions. A recent crystal structure of MutY with a bound OdG:dA mismatch has indicated that MutY recognizes the OdG, in part, through hydrogen bonding at both the N7-hydrogen and the C8-oxygen of OdG. Interestingly, though dG has neither a N7-hydrogen or a C8-oxygen, MutY can still efficiently remove adenine from dG:dA mismatches, though at a reduced rate as compared to OdG:dA mismatches. Thus, in order to gain insight into the importance of the N7 and C8 positions to MutY substrate recognition, we studied the ability of MutY to remove adenine opposite seven OdG/dG analogues that differ at either the N7, the C8, or both positions. It was found that all seven analogues were active with MutY, suggesting that alterations in the imidazole ring of dG are well tolerated by the glycosylase.