One hundred and ninety-two stands in six stand composition/past management strata on the Fremont and Ochoco National Forests were surveyed to evaluate differences in amounts of pest-caused true fir mortality. Surveyed stands with true fir overstories had significantly more fir mortality than those with pine overstories, and most true fir mortality in the latter type of stand was not pest-caused. Among surveyed stands with true fir overstories on the Ochoco National Forest, particularly large amounts of mortality (23 percent of the true firs dead), were observed in unentered stands. Most mortality in such stands was caused by laminated root rot and fir engraver beetles. Losses were less but still high in stands that had one harvest entry ( 15 percent of the trees dead) or multiple harvest entries (9 percent of the trees dead). Losses in these stands were caused by annosus root rot, Armillaria root rot, stem decays, and fir engraver beetles. Among surveyed stands with true fir overstories on the Fremont National Forest, by far the greatest amount of mortality (23 percent of all true firs dead), was found in stands that had multiple harvest entries. Significantly less mortality was observed in stands that had one or no entries (6 and 2 percent of the true firs dead, respectively). Most true fir mortality on the Fremont was caused by annosus root rot acting alone or with fir engraver beetles. The great amount of annosus root rot in entered stands on both Forests reflects the efficient use of stumps as infection courts by Fornes annosus and shows how this pathogen can become a serious threat in managed stands.