Human genome is exposed to the variety of damaging factors, such as ionizing radiation. 5',8-cyclo-2'-deoxypurines (cdPus) are well described unfavorable outcomes of DNA damage, especially devastating as a part of clustered DNA lesions (CDL). Since cdPus are not repaired by base excision repair (BER) and poorly repaired by nucleotide excision repair (NER), it is important to unveil the mechanisms of cdPus action within the genome. In this study the influence of both 5'S and 5'R diastereomers of 5',8-cyclo-2'-deoxyguanosine (cdG) on the activity of OGG1 and FPG was examined. Synthetic oligonucleotides containing cdG and two molecules of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) were designed as model of single-stranded CDL. The activity of both enzymes increased in the presence of cdG, compared to the control DNA strands, and the increase was greater in the case of 5'R diastereomer. These results are supported by previous studies concerning cdPus and confirm the impact of lesions proximity on the DNA repair efficiency. Due to the biological importance of cdPus, it is necessary to understand the mechanisms of lesions recognition by repair proteins in further studies.