Institut de Chimie des Substances Naturelles
 The Institut de Chimie des Substances Naturelles (Institute for the chemistry of natural substances) is part of the Centre national de la recherche scientifique France's most prominent public research organization. It is located at Gif-sur-Yvette near Paris. The ICSN is France's largest state-run chemistry research institute. It was built in 1959 and it employs over 300 people.