The Registry of introduced terrestrial molluscs in Belgium is a species checklist dataset published by the Royal Belgian Institute for Natural Sciences (RBINS). It contains information on all (29) non-native terrestrial molluscs occurring in the wild in Belgium since 1800. The list was originally compiled for EASIN (https://easin.jrc.ec.europa.eu/easin) and is based on a literature survey and information from the collections of the Royal Belgian Institute of Natural Sciences (RBINS). Here it is published as a standardized Darwin Core Archive and includes for each species: the accepted scientific name and associated synonyms, higher classification, detailed taxonomic background information and stable taxon identifier (in the taxon core), the (confidence regarding the) presence in Belgium, the year of the first introduction (first report), sometimes the last assessment/observation in Belgium and detailed verbatim information about the recorded introductions (in the distribution extension), vernacular names (in the vernacular names extension), the pathway(s) of introduction, native range(s) and degree of establishment in Belgium (in the description extension) and a detailed overview of the consulted resources (in the literature reference extension). The dataset can be used for researching and managing terrestrial alien molluscs or compiling regional and national registries of alien species. Issues with the dataset can be reported at https://github.com/trias-project/alien-mollusca-checklist We have released this dataset to the public domain under a Creative Commons Zero waiver. We would appreciate it if you follow the GBIF citation guidelines (https://www.gbif.org/citation-guidelines) when using the data. If you have any questions regarding this dataset, don’t hesitate to contact us via the contact information provided in the metadata or via https://twitter.com/trias_project. This dataset was published as open data for the TrIAS project (Tracking Invasive Alien Species http://trias-project.be, Vanderhoeven et al. 2017), with technical support provided by the Research Institute for Nature and Forest (INBO). It is selected as one of the authoritative sources for the compilation of a unified and reproducible checklist of alien species in Belgium.