The invention concerns a process and assistance system for warning of an unauthorized access to a parked vehicle. The process includes a first step for providing a communication as to whether the vehicle is at least partially unlocked. In a second step, in the case of an affirmative communication, the transmission of the current location of the vehicle takes place. In a third step, a comparison is made between the current location with at least one predetermined home location. In a fourth step, in the case in which the current location does not correspond with at least one home location, a wireless transmission of a warning signal to a mobile unit is given. In a fifth step, following the receipt of the warning signal by the mobile unit, a warning that is perceptible optically and/or acoustically and/or haptically is undertaken.