Aggressive traffic behaviour means that a road user behaves in such a way that he/she deliberately causes damage to another road user or threatens to do so. Generally speaking, the cause is an incident in traffic which gives the aggressor the feeling that he/she was deliberately harmed by someone else and he now seeks retaliation or satisfaction. Well known examples are making obscene gestures, swearing, hitting the car, tailgating, and cutting in. In serious cases, somebody is forced to stop and a fight begins that can result in casualties. There is practically no objective data about how often traffic aggression occurs, nor about the road safety consequences. The possibilities of reducing aggression in traffic are limited and, for the time being, must be looked for in information and education.