Estonian Naturalists' Society (Estonian: Eesti Looduseuurijate Selts, ELUS) is the oldest Estonia-based society of naturalists. It was founded in 1853, and since establishing has been the major scientific organisation focusing on natural history of Estonia.
The Society is based in Tartu. It has been associated with Tartu University and the Estonian Academy of Sciences. The society still operates (2018) and claims to be the oldest scientific society in the Baltic states.
The Society owns a rich library that is specialised on the publications about Estonian nature.