The continuous measurement of the moisture content of soil, and the suction or tension at which soil moisture is held, is of importance in both agriculture and civil engineering. In this paper an analysis is made of the electrical resistance method of measuring soil moisture. It is shown that whilst the method can be used to determine soil suction with a reasonable accuracy, its application to the measurement of moisture content is limited. A new type of concentric electrode moisture gauge of very small size and rapid response is described.