Abstract: Two anti-backdraft shutters are each supported in an exhaust fan assembly casing on a set of upper and lower parallel support arms. Outer ends of each set of these arms are pivotably mounted in the casing in closely adjacent relation to the other set on substantially vertical axes in closely adjacent relation to an exhaust fan motor and between the motor and an intake port defining the intake end of the casing. The shutters can move between an open position in almost parallel relation to each other with the fan-motor in between under the action of air being exhausted, and a closed position where the shutters close off the entire intake port. A coil spring urges the shutters to move toward closed condition.