Guanine rich nucleic acids can self-assemble into four-stranded guanine (G)-quadruplex structures that have been identified in eukaryotic telomeres, as well as in non-telomeric genomic regions, such as gene promoters, recombination sites and DNA tandem repeats, finding wide applications in areas ranging from medical chemistry to nanotechnology and biosensor technology. In addition to classical methodologies for studying G-quadruplex structures, such as circular dichroism, nuclear magnetic resonance or crystallography, the electrochemical methods present very high sensitivity and selectivity and have been used for the rapid detection of the conformational changes from single-strand to G-quadruplex. This review is focused on the recent advances of G-quadruplexes electrochemistry and the design of strategies for the fabrication of G-quadruplex-based biosensors with electrochemical detection, in particular G-quadruplex aptasensors and hemin/G-quadruplex peroxidase-mimicking DNAzymes biosensors. (C) 2013 Elsevier Ltd. All rights reserved.