From time to time newspapers bring reports on "earth rays" and their alleged damaging effects on health. There is, however, no objective evidence which suggests the existence of earth rays. In spite of this, dowsers claim that earth rays are a main cause of disease, also in children. In this study we wanted to evaluate, using a double-blind design, the alleged effects of earth rays on young children. A total of 44 children in four nursery schools in the Bergen area were recruited. Two dowsers and one interviewer visited the homes of all the children. The dowsers evaluated the presence of earth rays over the child's bed while the parents were interviewed in an independent procedure about the child's medical history over the past 12 months. Whether or not earth rays where found over the child's bed, there where no differences in the reported health of the child with regard to upper and lower respiratory tract infections, stomach aches, allergies or sleeping habits. Parents' report on restlessness and hyperactivity were also the same. The study failed to find any health effects, adverse or not, of earth rays.