The extent and causes of winter desiccation were studied in 3 tree-line spp. on Mount Washington, New Hampshire [USA]. Excessively low relative water contents were not found in intact foliage of balsam fir (Abies balsamea [L.] Mill.) or black spruce (Picea mariana [Mill.] BSP.) during the winter. Relative water contents were lowest following damage by ice abrasion and in intact stems of paper birch (Betula papyrifera Marsh.). Winter transpiration in conifer foliage is very low apparently due to several dormancy-related mechanisms. Transpiration is further reduced by high wind speeds which maintain thermal equilibrium between leaf and air. Winter desiccation is apparently not universal at tree line and is probably related to factors other than the high-wind regime.