In a method for preventing collisions of vehicles, first the surroundings of a vehicle 2 and motion parameters of the vehicle 2 are detected by means of sensors 2.1, 2.2, 2.3, 2.4, 2.5. From the output signals of the sensors, a failure-to-yield criterion and a collision risk criterion are derived. From a combination of the failure-to-yield criterion and the collision risk criterion, a risk level is ascertained. Depending on the particular risk level ascertained, finally, steps for reducing the risk of collision are initiated.