Winona Lake Research Natural Area is a 280-acre (110 ha) area of old-growth forest in Saline County, in the U.S. state of Arkansas. It is located in the Winona Ranger District of the Ouachita National Forest, on the south end of the Fourche Mountains, near Jessieville, Arkansas. The area was designated a National Natural Landmark in 1977. The land is owned by the U.S. Federal Government and is administered by the USDA Forest Service.