A systematic and biogeographical list of the Lepidoptera (butterflies and moths) of Switzerland comprising 3851 species is presented. Of those 183 species have been erroneously reported from Switzerland, so that the number of currently accepted Swiss species is 3668. Notes are provided for many species, covering uncertain or interesting records and systematic or taxonomical issues. The numbering and nomenclature of the species follow the publication The Lepidoptera of Europe by Karsholt & Razowski (1996). More recent nomenclatorial changes are mentioned in the notes. The distribution in Switzerland is documented for each species on the basis of its occurrence in six biogeographical regions.