The protection of long time unmanaged forests, formally defined for the first time in the Cévennes National Park, is part of the continuum of a long-lasting history of natural space preservation. These forests cover around 41,000 ha in mainland France in 2022 (0.24% of forests), mainly thanks to integral biological reserves, and significantly contribute to preserve remarkable species and forest ecosystems, sometimes over large unfragmented areas. However, their number is still too low to ensure the conservation of all forest species. These forests are also preferential observation fields for long-term scientific research. Looking for the best compromise between protection stakes and feasibility, the protection of long time unmanaged forests requires deploying different levers of social acceptability. The resulting experience will prove highly useful to implement the national strategy for protected areas.