The Flatside Wilderness is a 9,507-acre protected area in the U.S. state of Arkansas. It is one of six wilderness areas in the Ouachita National Forest and also the easternmost. Outdoor enthusiasts can enjoy the area in a number of ways, including an 8.9-mile section of the Ouachita National Recreation Trail.

The Ouachita National Forest is a vast congressionally-designated National Forest that lies in the western portion of Arkansas and portions of extreme-eastern Oklahoma, USA.