Invasive species - Chinese muntjac (Muntiacus reevesi) in Flanders, Belgium is a sampling event dataset published by the Research Institute of Nature and Forest (INBO). It contains information on 120 sampling events with 64 validated occurrences of invasive muntjac (M. reevesi) and native roe deer (Capreolus capreolus) starting from 2004. These occurrences mainly originate from casual observations or cullings of individuals. Here the dataset is published as a standardized Darwin Core Archive and includes for each event: a stable eventID, date and location of observation, and a short description of the sampling protocol (in the event core), supplemented with specific information for each occurrence: a stable occurrenceID, the scientific name and higher classification of the observed species, the number of recorded individuals, sex, life stage, and a reference to the observer and identifier of the record (in the occurrence extension). Issues with the dataset can be reported at https://github.com/inbo/data-publication/issues We have released this dataset to the public domain under a Creative Commons Zero waiver. We would appreciate it if you follow the INBO norms for data use (https://www.inbo.be/en/norms-data-use) 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 opendata@inbo.be. 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).