The Pasayten Wilderness is a 531,539 acres (215,106 ha) protected area located within Okanogan–Wenatchee National Forest and Mount Baker National Forest in Washington state, centered on the Three Forks of the Pasayten River, a tributary of the Similkameen River. Although part of the wilderness lies in Mount Baker-Snoqualmie National Forest, the largest section falls within the boundaries of Okanogan National Forest, which has responsibility for the wilderness's management. The wilderness is bordered by the Stephen Mather Wilderness to the west. The northern boundary of the wilderness is the Canada–US border. Across the border are Manning Provincial Park and Cathedral Provincial Park. The wilderness area is adjacent to the Ross Lake National Recreation Area to the west, and North Cascades National Park beyond that. The Pacific Crest National Scenic Trail has its northernmost section in this wilderness. The western part of the wilderness features dramatic views and peaks of the northern Washington Cascade Mountains while the eastern section is known for its grasslands and Alpine tundra. The tallest point in the Pasayten is Jack Mountain.

The Okanogan–Wenatchee National Forest is a U.S. National Forest located in Okanogan County in north-central Washington, United States.