Pacific Northwest National Forest Act of 1990 - Establishes the following primary purpose land use designations in order to assure balanced multiple use of national forest lands and waters within Region Six (Pacific Northwest Region) of the National Forest System: (1) ancient forest protection area; (2) timber management area; (3) recreation area; (4) statutory wilderness area; and (5) other classification area. Prohibits the alteration of any designation sooner than 15 years after it has been made.

Sets forth designation criteria and management requirements for primary purpose land uses. States that it is the intent of the Congress for the designation of ancient forest protection areas and statutory wilderness areas to provide all necessary protection of wilderness interests in Region Six.

Provides for joint State and Federal management of timber management areas.

Grants exclusive jurisdiction for review of Region Six forest plans and timber sales to the United States Court of Appeals for the Ninth Circuit.