We review various methods developed for human perspiration measurement and their physiological applications, with special reference to the performance and application of a new home-made ratemeter and instrumentation with a microscope. Many kinds of humidity sensor based on humidity-sensitive electrical properties have been investigated and placed on the market. Recently a capacitive thin-film humidity sensor was constructed and confirmed to be one of the best humidity sensors for accurately and quickly detecting changes in the relative humidity of gas-dow perfused through a ventilated chamber for human perspiration measurement. In this paper we also introduce a new home-made ratemeter with a capacitive humidity sensor, the electrical output of which is not disturbed by changes in ambient temperature, and new instrumentation for directly observing drops of sweat secreted from eccrine glands in human skin and simultaneously measuring the change in amount of perspiration at the same area of skin. Finally, we review physiological applications of the methods for measuring human palmar perspiration including emotional sweating.