Electronic systems can cause electromagnetic interference that disrupt radio and wireless systems. This is typically unintentional interference and it has been known for about a century now. Nowadays, dedicated jamming equipment is sold openly and at low cost via Internet. This implies that intentional interference can become more common. In this paper results from a measurement campaign of the interference situation for GPS, in Europe, is presented. The used interference detection equipment where placed in seven different countries, total eleven sites where covered in a three month period. The results show an increased number of interference event in busier areas, e.g city centers, major roads. Classification of the detected interference events shows that both unintentional and intentional jamming devices exists.