Background- Due to international trade, climate and ecological changes, and tourism, mosquito (Culicidae) species are transported, dispersed, or introduced and eventually become established into new territories. Since 2017, a nationwide three year project started in Belgium (MEMO: Monitoring of Exotic Mosquitoes), which is funded by the federal government, and which aims at detecting and monitoring the occurrence of exotic mosquito species (EMS) in the country. Activities started with mosquito sampling in 23 points of entry (PoE s), using adult trapping, as well as egg and larval sampling. Results- Collected EMS are barcoded to verify their morphology-based species identifications. Also, 5% of the yearly mosquito specimen collection is verified using DNA-barcoding technology (about 1000 specimens), as quality control measure of the morphology-based species identification. In 2017, 15 native species belonging to five genera were identified and confirmed by DNA-data. Additionally, all intercepted EMS could be distinguished from the native Culicidae. Presently, four EMS were collected once or multiple times at one or multiple PoE s: Aedes koreicus; Aedes japonicus; Aedes albopictus; and Anopheles pharoensis. In 2018, Aedes albopictus was intercepted at five PoE s, three of which for the first time. Also, a new species for Belgium, Culiseta longiareolata, was recorded during this nation-wide monitoring project. Significance- EMS were found to enter Belgium effectively and repetitively through different introduction pathways: via lucky bamboo and used tyre transport, ground traffic, but also possibly by natural dispersal. In this perspective, MEMO will contribute to a better understanding of the introduction process of the different exotic species by providing information on their status (introduction, establishment or spread), which is essential to guide EMS surveillance and their control. Also, the DNA-based approach to validate the morphological identification is essential to ensure the quality of the identification and to identify stadia which cannot be identified based on morphological characteristics.