This review is focused on genotoxic 2-nitrofluorene, which is a marker for the presence of nitrated polycyclic aromatic hydrocarbons, and summarizes the current knowledge about the negative effects of 2-nitrofluorene and its metabolites on living organisms, especially on their DNA. These findings obtained via in vivo investigations are compared with information obtained using electro-chemical DNA biosensors, which represent very promising in vitro alternative to the study of processes proceeding in living organisms during the interaction of their DNA with various xenobiotic compounds.