Antibase 2007 is a comprehensive database of 33，557 natural compounds from micro-organisms and higher fungi. The data in AntiBase have been collected from the primary and secondary literature and then carefully checked and validated. AntiBase includes descriptive data (molecular formula and mass， elemental composition， CAS registry number); physico-chemical data (melting point， optical rotation); spectroscopic data (UV， 13C-NMR， IR and mass spectra); biological data (pharmacological activity， toxicity); information on origin and isolation and a summary of literature sources. The total number of occupied database fields is about 400，000. A unique feature of AntiBase is the use of predicted 13C-NMR spectra for those compounds where no measured spectra are available. These spectra have been produced using the spectrum prediction program SpecInfo. Calculated high resolution molecular masses are included. Availability： AntiBase 2007 is available in the database formats ISIS/Base (MDL) and ChemFinder (CambridgeSoft).