Background - During the chikungunya outbreak on Réunion Island in 2005–2006, recommendations regarding individual mosquito protection measures using repellents for young children varied. To assess the frequency and identify patterns of use, as well as the range and incidence of adverse effects of topical insect repellents in young children, the Tropical Pediatrics Group and early childhood professionals on the island conducted a retrospective cross-sectional survey (the "Infant Insect Repellent Réunion 2009 - INR 2009"). Materials and Methods - The target population consisted of children under 30 months of age residing on the island during the chikungunya epidemic. The questionnaire was randomly administered to parents of children seeking medical care and to nursing students who were mothers. The survey was conducted face-to-face with parents at maternal and child health centers and daycare centers in the island’s four main regions from March 15 to April 15, 2009. The items covered sociodemographic and medical factors and assessed the use of insect repellents and mosquito nets among children. The selection method was exhaustive. Data from the preliminary survey were included in the analysis of results. A description of the variables was performed in terms of prevalence, including an analytical component and comparisons of means, medians, and Chi-square tests (p<0.05). Results—382 children under 30 months of age representative of the target population were included. At least one topical insect repellent was applied to 74% of these infants to protect them from mosquito bites during the day during the chikungunya outbreak. The main active ingredients used were IR3535® (77%) and citriodiol (17%). These products were applied more than once a day in 79% of the children. The median duration of use of these products per child was between 3 and 6 months. Mild skin side effects (7.9%) and systemic allergic reactions (1.8%) were observed. Three children experienced febrile seizures after applying insect repellent (1.1%), although it could not be determined whether these were attributable to the products. Factors associated with the use of insect repellent in children included age > 6 months, a father in the workforce, a home with a garden, and residence in the eastern part of the island (p<0.01). Seventy percent (70%) of the children were also protected by mosquito nets during the day. The estimated prevalence of chikungunya was 8.2% (±4%). Discussion - Pragmatic adherence to national recommendations regarding the use of insect repellents in young children was observed. Non-recommended usage practices were identified regarding the age limit for use, the number of daily applications, and the duration of use. In addition to mosquito net protection, the use of insect repellents may have contributed to the low prevalence of chikungunya in this population. Further studies would be needed to confirm this. Conclusion - These data show that during the epidemic, IR3535® and citriodiol were widely used to protect children under 2 years of age, and this practice was well tolerated. Misuses necessitate an objective assessment of their consequences and adequate information for healthcare professionals and parents regarding vector protection for young children. (R.A.)