A survey for incidence and distribution of root diseases was conducted on the Kootenai National Forest using timber inventory subcompartments as primary sample units. Root diseases were located within 23 of 75 sampled subcompartments. At least 1.1 percent of the commercial forest lands within the Forest are infested with root diseases. Large active disease centers occupy more than 1,550 ha (3,830 acres) of forest land. Major pathogens encountered were Phellinus weirii, Armillaria mellea, and Phaeolus schweinitzii. P. weirii was found mostly within the Cabinet Ranger District; other pathogens were distributed throughout the Forest. Bark beetles often infested root-diseased trees. Most root disease was found within the Pseudotsuga menziesii, Abies grandis, and Tsuga heterophylla series of habitats. Management procedures for reducing losses in root-diseased stands are discussed.