Hainich is a forested hill chain in the state of Thuringia in Germany, between the towns of Eisenach, Mühlhausen and Bad Langensalza.
The Mühlhäuser Stadtwald in the northern part of Hainich is the largest municipal forest in Thuringia.
The western edge of Hainich leads to Lempertsbach and Lauterbach valley and is steeper than the eastern slope.
The following communities take part of Hainich: Eigenrieden, Heyerode, Hallungen, Nazza, Mihla, Lauterbach, Bischofroda, Berka v.d Hainich, Behringen, Reichenbach, Craula, Zimmern, Alterstedt, Weberstedt, Mülverstedt, Flarchheim, Kammerforst, Oppershausen, Langula, Niederdorla, Oberdorla, Mühlhausen.
Central parts of Hainich National Park, so Weberstedt and Schöndorf forest, are rich on dead wood.
On 26 August 2005 nearby Thiemsburg forester's house in the southeast of Hainich one of the largest tree canopy paths was declared to be open.
It is the most important institution for environmental education in Thuringia and a platform for ecological research in the treetop region of a broadleaf forest.