In recent years a scientific strategy has been developed in the context of the problem of invasive plant species in Belgium, in particular in the INPLANBEL project (http://www.fsagx.ac.be/ec/inplanbel/Pages/intrologo.htm  ).  In coordination with the Biodiversity platform, the scientific community is currently building list of exotics classified according to their degree of invasion and their socio-economic/environmental impact (in preparation).  This approach is rather static and it is necessary to complement it with risk analysis providing information on current and future risks.  No such analysis have been conducted at the Belgian scale up to now for exotic plants.  In order to built up competencies for such analysis and to deliver PRA for exotic plants at the end of the project, PRA will be realized for three plant species (from the proposed list) that represent contrasted situations in term of impact and current invasion success : Ambrosia artemisiifolia, Senecio inaequidens, Falopia spp.  Ambrosia artemisiifolia has been introduced from North America in South France.  It is currently expanding northward but is still consider as sporadic in Belgium.  The species has high detrimental impact on public health due to its allergenic pollen and it is worth evaluating the risk for future expansion in Belgium (Dahl et al., 1999).  S.inaequidens has been introduced from South Africa in Belgium and is now one of the most expanding exotic plant species. Nevertheless, it is considered that the environmental impact of the species is low (Ernst, 1998).  Fallopia spp. is a complex of related species introduced in Europe from Asia. It forms one of the most invasive plant species in Europe with recognized detrimental effect on biodiversity, river management, road side management, soil erosion,…(Child & Wade 2000).  For Senecio, an EPPO data sheet is already available at the European Level (http://www.eppo.org/QUARANTINE/plants/Senecio_inaequidens/SENIQ_ds.pdf).  This case study will then serve as a test of the possibility to transfer conclusions of PRA from large geographic scales to more restricted scales.  The EPPO pest risk assessment scheme requires scores on a 1–9 scale to be assigned to 48 questions covering the potential for entry, establishment and impacts in a defined area (MacLeaod &Baker, 2003).  Combining those three contrasted situations will help to test the pertinence of EPPO PM5/3 standards for exotic plant species and serve to standardize responses (scores), thus enhancing the ability to compare the risks posed by different pests at the Belgian scale.