Anders Run Natural Area is a 96-acre (39 ha) protected area in Warren County, Pennsylvania. It is part of Cornplanter State Forest.
It contains about 50 acres (20 ha) of old-growth forest including the tree species Eastern White Pine, Eastern Hemlock, Cucumber Magnolia, American Beech, American Hornbeam, Black Cherry, and oaks. Although parts of the natural area were logged during the first two decades of the 19th century, tree rings of fallen trees have revealed 200-year-old white pines and 400-year-old hemlocks. In addition to being the oldest, these two tree species are also the largest, and some of the white pines are over 4 feet (1.2 m) in diameter at breast height.
In addition to its forests, the Natural Area also has a stream with native trout and fine stands of wildflowers. There is a historic residence on the property built in 1841 called the "Little Stone House".
The Natural Area has about 2 miles (3.2 km) of hiking trails.