Leakage-free integrated electronic switch

An electronic switch in integrated circuit from includes a first n-channel MOS transistor and a second n-channel MOS transistor with respective source-drain paths in series between an input terminal and an output terminal, and a third n-channel MOS transistor connected between a connection node between the first and second transistors and a supply terminal. The gate electrodes of the first and second transistors are connected together to a first control terminal and the gate electrode of the third transistor is connected to a second control terminal of the electronic switch. The first and third transistors are formed in a first p-well and the second transistor is formed in a second p-well, insulated from the first. A circuit branch which is identical, but provided by p-channel MOS transistors is also provided between the input and output terminals. The electronic switch is usable in circuit applications with transient voltages which may go beyond the supply voltage of the integrated circuit in a positive or negative direction.