The many different approaches in which electrochemical methods are used to detect DNA hybridization, as the basis of a DNA biosensors, are reviewed. Transduction of the hybridization event can be divided into two broad classes, approaches where a redox active species is used as a label and those where changes in the DNA interface are monitored electrochemically without the use of any labels. Important criteria in fabricating the DNA recognition interface on an electrode and future challenges are also discussed.