CSDB (the "ClusScan DataBase") is a bioinformatics database containing genetic and biochemical information on natural products synthesised by Thiotemplate Modular Systems (TMS). These systems include polyketide synthase (PKS), non-ribosomal peptide synthetase (NRPS), NRPS-independent siderophore (NIS) synthetase and hybrid synthase/synthetase enzymes annotated using the ClustScan suite of programs. CSDB contains all data starting with genomic actinobacterial DNA sequences together with the DNA and protein sequences annotating the genes, modules, domains and corresponding linkers and dockers of TMS clusters. It also contains all known polyketide and peptide building blocks in the form of isomeric SMILES (Simplified Molecular Input Line Entry System), along with the programmed logic that allows prediction of linear and cyclic polyketide and peptide chains and aglycons in the 2-D or 3-D forms suitable for further computer processing. The database is fully searchable using TMS gene cluster annotations as well as TMS compound structures. CSDB data can be manipulated using a number of conventional bioinformatic tools.