Dengue is the most widespread arbovirus disease in the world, where it continues to spread. It is transmitted by the Aedes aegypti and Aedes albopictus mosquitoes. With the spread of the Aedes albopictus vector and the high volume of travel, the disease is no longer confined to the intertropical zone, and transmission clusters have been documented in temperate regions. Thus, in mainland France, where Aedes albopictus has been established and has been spreading since 2004, two episodes of local dengue transmission occurred, in 2010 and 2013. Prevention measures for dengue and chikungunya, which share the same vectors, have been implemented annually since 2006 in the metropolitan departments where Aedes albopictus is established. They aim to prevent or limit local transmission of these arboviruses. These measures rely on a system of human and entomological epidemiological surveillance and on vector control measures that combine the elimination of larval breeding sites, personal protection, and, when indicated, chemical mosquito control. In the presence of suggestive symptoms, such as fever accompanied by pain, dengue and chikungunya should be considered as possible diagnoses, particularly following a stay in an area where the virus is circulating, but also in individuals residing in or having visited metropolitan France in an area where the Aedes albopictus mosquito is established, during its active period from May 1 to November 30. The dissemination of prevention messages, community mobilization (control of larval breeding sites, personal protection), and the reporting of cases to regional health agencies (ARS) are key elements in preventing local transmission of dengue, as this risk increases each year. (R.A.)