An attempt is made to describe from an unified point of view the electric properties of liquid metals and semiconductors, including the critical region of temperatures and pressures for metals. Various models are discussed for the description of the electric properties of liquid metals and semiconductors, for which many experimental and theoretical investigations are known. At temperatures and pressures above critical, the accumulated experimental and theoretical material is not as extensive, but even now certain conclusions can be drawn concerning the character of the metal-dielectric transition during the continuous change from the liquid to the gaseous state.