The present invention relates to a method for assisting the driver of a motor vehicle with a fishtailing trailer. A vehicle with a fishtailing trailer can be stabilized in an especially rapid manner in that, in a first state, the fishtailing of the trailer is analyzed by evaluating at least one vehicle state variable, and when critical fishtailing is detected, a warning is output to the driver in a second state so as to induce the driver to brake, and the driver—provided he initiates braking—is assisted in the braking operation by automatic actuation of the vehicle brakes, a brake pressure being set at which the most optimal vehicle deceleration possible is achieved.