DNA is a unique material for nanotechnology, since it is possible to use base sequence to encode instructions for assembly in a predetermined fashion at the nanometer scale. The exact spatial positioning of materials is crucial for future development of complex nanodevices, and the emerging field of DNA-nanotechnology is now exploring DNA-programmed processes for the assembly of organic compounds, biomolecules, and inorganic materials.  This Perspective article was written by Kurt Gothelf at Aarhus University, Denmark, and Thomas LaBean at Duke University, USA.