An electrically-operated disc brake assembly for vehicles is disclosed in which a friction member (12) is adapted to be applied to a rotatable brake disc by a brake-applying means including an electric motor (11), and transmission means in the form of a linear actuator (10) comprising a screw device adapted to apply an axially-directed brake-applying force to the friction member in response to operation of the motor. The screw device (10) comprises inner and outer co-operating screw-threaded members (14, 15), and one of the members is adapted to co-operate with the armature (15) of the electric motor.