The invention relates to a method and device for braking the rotor of a wind energy plant, comprising rotor blades (3) mounted to rotate on the rotor with electrical devices in the rotor hub (2), such as an actuator (4, 5) for the rotation of the rotor blades (3), whereby on drop-out of the power supply to the electrical devices (4, 5), a rotor brake is activated (11), whereupon the rotor blades (3) as a result of the braking torque of the rotor brake (11) are rotated into the feathered position by means of the inertia thereof.