Significant recent progress has been made in the development of microfabricated nanofluidic devices for use in the biomedical sciences. Novel nanotechnological approaches have been explored in view of a more individualized medical approach. Much of the development has been fuelled by the advantages derived from utilizing nanoscale phenomena to manipulate fluid samples or mediate drug delivery. As such, we present a comprehensive review of nanochannel technologies, highlighting their potential for diagnostic and therapeutic applications.