Although lichens have been the subject of renewed interest for many countries worldwide, this has not been the case for Tunisia where much of the territory continues to be largely under-explored. In order to promote lichenological research in Tunisia, a checklist was published in 1996 together with an historical overview and a bibliography compiled from a wide range of published sources. As a result of more recent field and herbarium work, a revised checklist containing 644 taxa (628 lichens and 16 lichenicolous and allied fungi) is provided, of which 230 taxa are additional to the previous checklist; it also takes into account the large number of changes to the nomenclature in recent years. Key words: North Africa, Mediterranean, species list, biodiversity.