The prevalence of obesity for children and adolescents in Germany has increased during the past 20 years. Because the success rate of therapy is low, prevention seems to be the only solution. Prevention should begin early in life. School is an ideal setting for the implementation of prevention strategies. The aim of this review was to compare results of school-based prevention programs and to identify effective methods. A systematic literature search for studies published between 1990 and 2009 was conducted. A total of 22 studies were considered for inclusion. Combined interventions including nutrition, physical activity, and television viewing modification are effective. The intervention should last for at least one year. Installation of water fountains in schools, implementation of the topics "sugar-containing drinks" and "television viewing" in the curriculum, modification of existing physical education and more physical activity during the school day are effective prevention strategies.