Our increasing understanding of peptide and protein folding and assembly raises new possibilities for engineering novel self-assembling supramolecular structures and bio-inspired materials. Here we focus on peptides designed de novo, and natural systems that have been engineered to form extended protein fibres. Potential applications of such assemblies include the preparation of functionalised biomaterials for the development of new diagnostic devices, scaffolds to recruit cells for cell/tissue engineering, and templates for the assembly of inorganic materials. (C) 2004 Elsevier Ltd. All rights reserved.