Abstract: A warning system is disclosed to be mounted on or incorporated in a vehicle, such as a truck or a bus, for warning vulnerable road users, such as cyclists and pedestrians, that the vehicle is going to make a turn, said warning system comprising one or more lights arranged to be mounted on or incorporated in one side of the vehicle near the front end thereof for illuminating at least a part of the surface of an area along the side and/or the front of the vehicle and a control system arranged to switch the one or more lights on and off, respectively, in accordance with a set of predefined conditions. Furthermore, a vehicle comprising such a warning system and a method of warning vulnerable road users is disclosed.