Ultrathin, perfectly ordered anodic aluminum oxide templates have been produced on supporting substrates by focused ion beam prepatterning. This fast, flexible approach produces pore arrays with both hexagonal and square geometries and allows control over the pore pitch and diameter. The orientation of ordering can be controlled with nanometer precision. Pattern transfer into Si produces pore densities of up to 10(11) in.(-2). (c) 2007 American Institute of Physics.