Neonicotinoids are systemic insecticidal substances used in agriculture to protect crops from pests; they are also used as biocides and veterinary medicinal products. There are currently five active substances in the class of neonicotinoids approved for plant protection purposes at the European level. Since the first marketing authorisations were granted for neonicotinoid products in the early 1990s, concerns have been expressed in several countries in Europe with regard to their possible impact on the health of bees. ANSES contributes to improving scientific knowledge in this area through its work on co-exposure of bees to stress factors and through its missions for the assessment of active substances and plant protection and biocidal products.