Aptamers have emerged as promising biorecognition elements in the development of electrochemical-based sensors. Aptamers, short oligonucleotides of DNA or RNA selected in vitro to bind a specific target, boast comparable binding affinities to antibodies, but possess superior chemical and biochemical stabilities. In addition, they require relatively simple synthesis protocols compared to the in vivo development of antibodies. Coupling the specific recognition abilities of aptamers with the selective and sensitive detection abilities of electrochemical signal transduction enables an almost unlimited number of strategies for generating biosensor architectures. Here we present a critical review of electrochemical sensing strategies employing aptamers through a presentation of the various signal transduction mechanisms employed. We find that, while there are numerous examples of aptamer-based sensors, the penetration of these platforms beyond the academic laboratory and proof-of-concept remains limited. We believe that aptamers will continue to be a focus in the development electrochemical sensors, although the limited number of proven aptamers hinders the progress of electrochemical, aptamer-based sensors from impacting fields beyond the electrochemical laboratory. However, considering the historical success of electrochemical-based sensors as well as the promise of selecting aptamers for virtually any target, we believe the future is bright for aptamers in electroanalysis and beyond. (C) 2014 The Electrochemical Society. All rights reserved.