The 4th European Union Science Olympiad was held in Brussels, Belgium on the 2nd – 8th April 2006. The Patron was Her Majesty, Queen Paola of Belgium, Mr. Victor Rasquin was the Director and Prof. Dr. Louis De Vos was Chairman of the Scientific Committee. The experiments were developed by and held in Vrije Universiteit van Brussel (VUB) and the Université Libre de Bruxelles (ULB). Twelve countries were represented by a total of 23 teams (69 Students) from Belgium, Cyprus, Estonia, Germany, Greece, Ireland, Latvia, Netherlands, Slovakia Spain, Sweden and the United Kingdom. Denmark sent an Observer.