Biosensors are the most commonly used sensors in medical and laboratory diagnostics. Electrochemical biosensors based on nucleic acids are sensors in which nucleic acids are used as a bio receptor and the electrode is used as a transducer that over recent decades, there has been a lot of research in this area. Most studies on these molecules are related to measuring nucleic acids in biological samples, identification of nucleotide sequences, and their interactions with some small molecules such as drugs or carcinogens. These measurements are performed using an electroactive indicator )indirect electrochemical detection) or by the intrinsic electroactivity of DNA (indicator free, direct electrochemical measurements). Considering the above, in this section, we study the application of nucleic acids based electrochemical biosensors in the detection of DNA damage, diagnosis of genetic defects, recognition of G-quadruplex structure, and measuring small amounts of some heavy metal ions.