The first comprehensive checklists since the works of Germain in 1916 are presented for the terrestrial Mollusca of São Tomé and Príncipe. The fauna currently known comprises 59 species for São Tomé, 45 for Príncipe, and a total of 86 species in the country as a whole. Seven species of terrestrial Gastropoda are newly described from the island of São Tomé and six more from the island of Príncipe. The genera involved are Cyathopoma (Cyclophoridae), Maizania and Thomeomaizania (Maizaniidae), Pseudoveronicella (Veronicellidae), Nothapalus (Achatinidae), Gulella and Streptostele (Streptaxidae), Truncatellina (Truncatellinidae), Afroconulus (Euconulidae), Principicochlea n. gen., Principotrochoidea n. gen., Thomithapsia n. gen. and Thomitrochoidea n. gen. (Urocyclidae). Most of these are from natural forest habitats and are likely to be singleisland endemics. Aporachis n. gen. (Achatinidae s.l.) and Apothapsia n. gen. (Helicarionidae) are also described to accommodate previously known species. Rachis burnayi (Dohrn) and R. eminula (Morelet) are placed in the genus Gittenedouardia. Additional new island records are of ten species on São Tomé, one on Príncipe and two more on both islands. These include six species of “microgastropods” with wider ranges in tropical Africa that are likely to be hitherto overlooked parts of the indigenous fauna and six anthropogenic introductions. Pseudopeas crossei previously known only from Príncipe and Bioko is newly recorded on São Tomé. More detailed taxonomic notes are provided on identification and delimitation of species and genera in Cyclophoridae/ Maizaniidae, Veronicellidae, Achatinidae, Cerastidae, Helicarionidae, and on the forgotten but apparently valid Pseudoveronicella thomensis (Veronicellidae).