AbstractNanoporous alumina membranes represent templates for the synthesis and alignment of filamentous nanostructured materials. Porous aluminium oxide (PAOX) membranes are ideal for high‐temperature synthesis. They are transparent, flexible, freestanding and thermally robust. Their pore sizes can be varied over a wide range. The membrane backside seems suited for structuring processes on the nanoscale, for which it may serve as a master. After introducing the formation process of PAOX membranes, synthesis of carbon nanotubes (CNTs) with different morphologies, their electrical field emission properties, and the formation of polymeric filaments and structured polymer surfaces with the aid of PAOX are reported in this microreview.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)