Fluidic systems with nanometre length scales enable sensitive analysis of DNA molecules. Nanofluidic systems have been used to probe conformational, dynamic, and entropic properties of DNA molecules, to rapidly sort DNA molecules based on length dependent interactions with their confining environment, and for determining the spatial location of genetic information along long DNA molecules. In this critical review, recent experiments utilizing fluidic systems comprised of nanochannels, nanoslits, nanopores, and zero-mode waveguides for DNA analysis are reviewed (161 references).