Literature pertaining to the impact of forest pests on timber productivity in the prairie provinces and Northwest Territories is reviewed. The discussion of impact is largely confined to growth loss and tree mortality, and quality reduction is considered in some cases. Potential and actual depletions caused by wood decay, armillaria root rot (Armillaria spp. ), lodgepole pine dwarf mistletoe (Arceuthobium americanum Nutt. ex Engelm.), hypoxylon canker of aspen (Hypoxylon mammatum [Wahl.] J.H. Miller), atropellis canker of pine (Atropellis piniphila [Weir] Lohman & Cash), spruce budworm (Choristoneura fumiferana [Clem.]), jack pine budworm (Choristoneura pinus Freeman), mountain pine beetle (Dendroctonus ponderosae [Hopk.]), forest tent caterpillar (Malacosoma disstria Hbn.), and the spruce beetle (Dendroctonus rufipennis [Kirby]) are outlined. The significance of various depletions are discussed.