Method for assisting a driver of a motor vehicle with a hitched trailer when parking the motor vehicle with the trailer in a parking space with the aid of a driver assistance device of the motor vehicle, having the steps of: a) determining at least an overall dimension of the motor vehicle with the hitched trailer in dependence on at least one specified dimension of the trailer by way of a computation device of the driver assistance device; b) capturing environment data relating to a parking space in an environment of the motor vehicle by way of a sensor device of the driver assistance device; c) parking the motor vehicle with the hitched trailer in the parking space, wherein c1) during the parking operation, the parking space is located at least in part outside a current capturing region (12, 12') of the sensor device of the motor vehicle; c2) at least one distance (d a, d b, d c) from the trailer to a boundary of the parking space is ascertained by way of the computation device in dependence on a position of the motor vehicle relative to the parking space and the overall dimension of the motor vehicle with the hitched trailer; and c3) if the ascertained distance (d a, d b, d c) is less than a specified minimum distance (d min), an alert is issued to the driver by way of the driver assistance device, characterized in that the determination of the overall dimension during the parking operation according to step c) is continuous and the overall dimension is determined in dependence on a hitching angle (α) of the trailer. a) determining at least an overall dimension of the motor vehicle with the hitched trailer in dependence on at least one specified dimension of the trailer by way of a computation device of the driver assistance device; b) capturing environment data relating to a parking space in an environment of the motor vehicle by way of a sensor device of the driver assistance device; c) parking the motor vehicle with the hitched trailer in the parking space, wherein c1) during the parking operation, the parking space is located at least in part outside a current capturing region (12, 12') of the sensor device of the motor vehicle; c2) at least one distance (d a, d b, d c) from the trailer to a boundary of the parking space is ascertained by way of the computation device in dependence on a position of the motor vehicle relative to the parking space and the overall dimension of the motor vehicle with the hitched trailer; and c3) if the ascertained distance (d a, d b, d c) is less than a specified minimum distance (d min), an alert is issued to the driver by way of the driver assistance device, characterized in that the determination of the overall dimension during the parking operation according to step c) is continuous and the overall dimension is determined in dependence on a hitching angle (α) of the trailer. c1) during the parking operation, the parking space is located at least in part outside a current capturing region (12, 12') of the sensor device of the motor vehicle; c2) at least one distance (d a, d b, d c) from the trailer to a boundary of the parking space is ascertained by way of the computation device in dependence on a position of the motor vehicle relative to the parking space and the overall dimension of the motor vehicle with the hitched trailer; and c3) if the ascertained distance (d a, d b, d c) is less than a specified minimum distance (d min), an alert is issued to the driver by way of the driver assistance device, characterized in that the determination of the overall dimension during the parking operation according to step c) is continuous and the overall dimension is determined in dependence on a hitching angle (α) of the trailer.