Assegaaibosch Nature Reserve, Nature reserve in Jonkershoek Valley, South Africa.

Assegaaibosch Nature Reserve is a protected area in Jonkershoek Valley spanning around 204 hectares along the Eerste River. It sits on the northeastern slopes of Stellenbosch Mountain and contains walking trails, picnic facilities, a historic homestead, and a trout hatchery building.

In 1682 Simon van der Stel granted Dirk Coetsee, captain of the Stellenbosch Infantry, land at the foot of Stellenbosch Mountain, where Coetsee founded the wine estate Coetsenburg. That same year Van der Stel promised him land higher in the Jonkershoek Valley, which Coetsee named Assegaaibosch and used mainly for livestock. The property was only registered in 1755, in the name of his son Gerrit Coetsee.

The name Assegaaibosch means "Forest of Assegaai" in Dutch and Afrikaans, after the many assegaai (Curtisia) trees on the estate; an assegaai is a traditional African weapon usually carved from Curtisia wood. The old manor house, a national monument, now serves as a guest house, and the stone trout-hatching house of 1893 also stands as a national monument.

The reserve lies about 9 km from Stellenbosch in the Jonkershoek Valley, bounded by Stellenbosch Mountain to the south and the Eerste River to the north. The Assegaaibosch Manor House now serves as a guest house, and CapeNature runs the property as a conservation station. Approach from Stellenbosch via the valley road.

The trout hatchery built beside Assegaaibosch in 1893 still stands as a stone building, though trout are no longer bred there because the species is exotic. CapeNature now uses the property as a conservation station, and the original hatching house is a national monument.