Hierarchical nanostructures are generated on substrates by combining a top-down ion beam lithography with a bottom-up self-assembly of block copolymers. The ion beam lithography images micron sized patterns of block copolymer thin films which contain nanometer sized microdomains. This approach provides a simple route to fabricate structures containing two different length scales, i.e. micrometers and nanometers, which may find a variety of potential applications in nanoscience and technology. © 2009 CPST.