Optothermal infrared spectrometry (OTIS) is a recently introduced method for specific measurement, in vivo, of water in the skin. In the present study the method proved well suited to register the increase in water content in stratum corneum following application of emollients. The results were compared with those obtained with a commercial instrument, the Corneometer, and the two methods were found to match very closely. Neither method indicated any difference in hydration of normal skin between young and elderly women. Evaporimetry was used to detect any influence on the water barrier function of the skin following application of emollients; even though the water content of the skin was significantly higher after emollient treatment, the transepidermal water loss remained unchanged.