Three Sisters Wilderness, Protected wilderness area in Cascade Range, Oregon, United States.

Three Sisters Wilderness covers 286,708 acres in the Cascade Range within Willamette and Deschutes National Forests. Its eastern portion holds North Sister at 10,090 feet, Middle Sister at 10,052 feet, and South Sister at 10,363 feet, plus Broken Top at 9,175 feet to the south. Fourteen glaciers lie among these peaks, including Collier Glacier, Oregon's largest, between North and Middle Sister.

Congress established the Three Sisters Wilderness on 1 January 1964, naming it for the three volcanoes inside its boundary. The peaks were known to pioneers as Faith, Hope and Charity. UNESCO designated the area a Biosphere Reserve in 1976, and the United States withdrew it from the programme in June 2017.

Pioneers called the three peaks Faith, Hope and Charity, names that survive in the surrounding landmarks The Husband, The Wife and the Little Brother. The wilderness also carries the name of the Three Sisters volcanoes it encloses. The 9.8-mile French Pete Trail and its old-growth forest, a nationwide political issue in the 1970s, lie on the western edge near Cougar Reservoir.

The wilderness is roadless: entry is on foot or horseback, with trailheads reached from Oregon Route 242 on the north side and forest roads near Cougar Reservoir on the west. More than 260 miles (420 km) of trails cross it, including 40 miles (64 km) of the Pacific Crest Trail. Weather changes quickly at these elevations, so carry layers and expect snow on the peaks into summer.

Collier Glacier, wedged between North and Middle Sister, is the largest glacier in Oregon. The wilderness holds 14 glaciers in all, including Broken Top's, and the headwaters of Wild and Scenic Whychus Creek rise inside its boundary.