Introduction: To prevent the spread of chikungunya and dengue in mainland France by travelers returning from or arriving in endemic areas, entomological and human surveillance is conducted annually in departments where the Aedes albopictus vector is present. In August 2015, two suspected cases of locally acquired dengue were reported in the Gard department to the Regional Health Agency and subsequently confirmed by the National Reference Center for Arboviruses. Epidemiological and entomological investigations were immediately initiated to control virus transmission. Methods: An active search for suspected cases was conducted (door-to-door survey, reporting of suspected indigenous cases, etc.), and an index case was sought among the imported dengue cases reported in 2015. Vector control measures (VCM) were implemented. Public meetings aimed at mobilizing residents of the affected neighborhood in managing the outbreak were organized. Results: Between August 8 and September 11, 2015, 7 locally acquired dengue cases (6 confirmed, 1 probable) were detected in a neighborhood of Nîmes. A probable index case, returning from French Polynesia, was identified. Six LAV treatments were carried out in the neighborhood, and three public meetings were organized through the elementary school and the neighborhood committee. Discussion: This episode constitutes the first significant dengue outbreak in metropolitan France. The cases occurred in an area colonized by Ae. albopictus for several years, despite low importation pressure (5 imported cases in the Gard department). The regular occurrence of dengue and chikungunya cases since 2013 in Provence-Alpes-Côte d'Azur and Languedoc-Roussillon reflects the growing risk of arbovirus outbreaks in mainland France.