The regions of Guadeloupe, French Guiana, and Martinique, and the communities of Saint Martin and Saint Barthélemy have implemented a specific local surveillance system to monitor the emergence of influenza A(H1N1) 2009. Following a containment phase focused on case detection and management, population-level surveillance was implemented, primarily based on data from sentinel physician networks and virological confirmations. Like all countries in the Caribbean region, the five territories experienced an epidemic linked to the 2009 H1N1 virus that began between August and September 2009. Despite similar dynamics, these epidemic waves exhibited specific characteristics in terms of magnitude and severity, with an attack rate ranging from 28 to 70 per 1,000 inhabitants and a hospitalization rate of 4.3 to 10.3 per 1,000 cases. The surveillance tools put in place provided a comprehensive and accurate overview of the epidemic’s characteristics and therefore appear entirely adequate for monitoring a potential new wave of the epidemic. Certain difficulties related to the specific geographic or health context of the affected regions (complexity of transporting samples for virological surveillance, concurrent occurrence of dengue epidemics) arose; conversely, certain local specificities (the presence of expert committees and active networks of sentinel physicians) facilitated the surveillance and management of the outbreak. (R.A.)