The flux of He and O2 through intact adult human skin was measured at various inspired concentrations and skin temperatures. The skin surface was then stripped with cellophane tape to alter the diffusional conductance of the stratum corneum. He flux for stripped skin was used to estimate skin perfusion as a function of local temperature, and diffusional conductance for O2 was estimated from O2 flux and perfusion. The flux of He or O2 at constant skin temperature can be related to inspired concentration by a simple linear model. Increasing surface temperature in the range 33–43 degrees C produced a much larger increase in O2 flux than in He flux for intact skin. Skin stripping greatly increased skin O2 flux. Estimated skin conductance for O2 showed a more marked temperature dependence than estimated skin perfusion. The results suggest that raising skin temperature in the range 38–43 degrees C has only a modest effect on skin perfusion and that stratum corneum conductance may have a major role in the large increase of O2 flux with temperature.