Abstract.Miller's theorem is generally used for approximate analysis of high-frequency amplifier circuits. That it can be used without much difficulty for the exact analysis of such circuits as well as others, including passive networks, does not appear to be widely recognized in the literature. Although formulated and proved in 1972, the dual of Miller's theorem has hardly ever been used. In this paper, we present the exact analysis of a number of circuits of practical interest with the help of either Miller's theorem or its dual or both, almost by inspection.