Control system for controlling flight in yaw of a rotorcraft equipped with an anti-torque rotor, the control system comprising: *) at least a first kinematic chain implementing a rudder bar driven by a human pilot, which is in communication with the anti-torque rotor via a remote mechanical transmission mechanism suitable for bringing about a variation of collective pitch of blades with which the anti-torque rotor is equipped, *) at least a second kinematic chain comprising actuators (6,7) for implementing the remote mechanical transmission mechanism, including a "trim actuator" and a "series actuator", the second kinematic chain implementing an autopilot which comprises calculation means, the implementation of the calculation means being placed under the dependence of a control button actuatable by a human pilot and giving rise to an activation of at least one of the actuators (6,7) for implementing said remote mechanical transmission mechanism in substitution for the first kinematic chain, *) inhibition means for inhibiting at least the second kinematic control chain, the implementation of which is placed under the dependence of detection means for detecting a driving of the rudder bar by the human pilot, characterised in that it comprises a third kinematic chain which incorporates objective piloting means, the implementation of which is placed under the dependence of a movable control member driven by the human pilot, the movable control member emitting a control signal to an objective computer which generates to the calculation means of the second kinematic chain a yaw control order relating to a state of progression to be achieved of the rotorcraft, the implementation of the third kinematic chain being placed under the dependence of the inhibition means, an intervention by the human pilot on the rudder bar deactivating the implementation of the third kinematic chain. *) at least a first kinematic chain implementing a rudder bar driven by a human pilot, which is in communication with the anti-torque rotor via a remote mechanical transmission mechanism suitable for bringing about a variation of collective pitch of blades with which the anti-torque rotor is equipped, *) at least a second kinematic chain comprising actuators (6,7) for implementing the remote mechanical transmission mechanism, including a "trim actuator" and a "series actuator", the second kinematic chain implementing an autopilot which comprises calculation means, the implementation of the calculation means being placed under the dependence of a control button actuatable by a human pilot and giving rise to an activation of at least one of the actuators (6,7) for implementing said remote mechanical transmission mechanism in substitution for the first kinematic chain, *) inhibition means for inhibiting at least the second kinematic control chain, the implementation of which is placed under the dependence of detection means for detecting a driving of the rudder bar by the human pilot, characterised in that it comprises a third kinematic chain which incorporates objective piloting means, the implementation of which is placed under the dependence of a movable control member driven by the human pilot, the movable control member emitting a control signal to an objective computer which generates to the calculation means of the second kinematic chain a yaw control order relating to a state of progression to be achieved of the rotorcraft, the implementation of the third kinematic chain being placed under the dependence of the inhibition means, an intervention by the human pilot on the rudder bar deactivating the implementation of the third kinematic chain.