The genome projects have now entered a rapid production phase with complete genome sequences and complete gene catalogues already available for a number of organisms and an increasing number expected shortly. In addition the new DNA and protein chip technologies can produce functional dataabout genes such as gene expression profiles at a rapid rate. There is therefore a large and ever increasing amount of data about genes and molecules. However there is still a huge gap between information at the molecular level and information at the level of integrated biological systems. It isthis gap that is addressed in Post-genome Informatics. Post-genome informatics is the analysis of biological functions in terms of the network of interacting molecules and genes with the aim of understanding how a biological system is organized from its individual building blocks. As well ascontaining a comprehensive survey of the database and computational technologies relevant to molecular sequence analysis, Post-genome Informatics will provide the reader with a conceptual framework and practical methods for the representation and computation of molecular networks.