A control circuit for an electric fan, has a MOSFET transistor connected essentially in series with the motor of an electric fan between the two terminals of a first D.C. voltage source and having its source terminal connected to the motor; a transistor driving stage, having an input intended to receive a pulse-width modulation control signal and an output connected to the gate terminal of the MOSFET transistor, and a bootstrap capacitor connected between a second D.C. voltage source and the source terminal of the MOSFET transistor. A controlled electronic switch having a parallel-connected diode for conducting current from the bootstrap capacitor to the motor is arranged between the bootstrap capacitor and the source terminal of the MOSFET transistor. The electronic switch has a control input or gate connected to the output of the transistor driving stage.