Over the past decade, many important technological advances have provided us with the toots and materials needed to construct functional nanostructure-based devices. The application of these devices in biosensing in place of conventional sensing technologies has led to improvements in sensitivity, selectivity, and multiplexing capacity. Here, we summarize the latest developments in the application of nanostructure-based biosensors with an electrical transduction mechanism, in ultrasensitive detection of biological entities, especially nucleic acids and proteins. Different types of the nanostructure-based biosensors, such as single-wall carbon nanotube (SWCNT), nanowire, nanogap, nanochannel, and nanoelectromechanical. system (NEMS)-based devices are reviewed in terms of their sensing performance and potential of future development. (C) 2009 Elsevier Ltd. All rights reserved.