Coarse root (≥0.15 cm diameter) biomass was measured by excavation in a wave-regenerated balsam fir forest at 1,220 m elevation on Mt. Moosilauke, White Mountains, New Hampshire. Logarithmic regressions of root dry mass on trunk diameter showed high correlation coefficients for all size classes of roots. Stand root biomass, calculated from these regressions and stem inventory data, increased from <0.1 kg/m² in 10-yr-old stands to a maximum of ~2.7 kg/m² in 45-yr-old stands, then decreased to 0.5 kg/m² in 80-yr-old stands undergoing overstory mortality. Comparisons are made with root biomass data from low-elevation balsam fir stands and from Japanese wave-regenerated fir forests. Forest Sci. 31:952-956.