Introduction The Registry of introduced terrestrial molluscs in Belgium is a species checklist dataset maintained by Thierry Backeljau at 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 RBINS. The dataset can be used for researching and managing terrestrial alien molluscs or compiling regional and national registries of alien species. The registry is maintained as a Google Spreadsheet and exported and uploaded here as an Excel file and csv files for each sheet. The dataset is also published for the TrIAS project (Tracking Invasive Alien Species http://trias-project.be, Vanderhoeven et al. 2017) as a standardized Darwin Core Archive, openly available on GBIF (https://doi.org/10.15468/t13kwo). Issues with the dataset can be reported at ... :