Field and laboratory gravimetric measurements were made of transpiration rates in several species of alpine plants from dry and moist environments in the Sierra Nevada. Maximum transpiration rates in the field ranged from 0.26 to 1.46 g/g f.w./hr and were highest for plants from moist sites. Ivesia gordonii, a dry site plant, was more efficient in using soil moisture near the wilting percentage than was Caltha howelii, a moist site plant. Caltha and Polygonum bistortoides, both from moist sites, showed midday reductions in transpiration rates during periods of high evaporation stress; most other species showed single-peaked diurnal transpiration curves. Sod blocks from moist sites had evapotranspiration rates ranging from ca. 1,500 to 3,00 g H2O/m2/24 hr while evapotranspiration for a dry site was calculated to be under 1,000 g H2O/m2/24 hr. Polygonum bistortoides phytometers containing plants originating from 2,743 m were established at that elevation and also at 2,438 m, 2,134 m, and 1,829 m, the latter two stations below the natural limit of the species. Transpiration rates remained steady at the two upper stations and the plants were healthy at the end of 48 hours. Rates at the two lower stations were twice those of the upper stations during the first 24 hours, were considerably reduced during the second 24 hours, and at the end of 48 hours the leaves were wilted and dried even though soil moisture was apparently adequate. Transpiration-rate characteristics appear to be of importance in determining local distribution patterns of alpine plants in the Sierra.