Numerous forms of therapy exist for the increasing number of obese children and adolescents in Germany, but these are heterogeneous and have not been evaluated. Access to health care, long- and short-term treatment outcome, as well as factors determining success of therapy were examined for the first time using standardized instruments to measure somatic and psychosocial variables. A total of 1,916 children aged 8-16 years from 48 (5 rehabilitation, 43 outpatient) institutions were examined. Data were collected for height, weight, blood pressure, and lipid status before treatment started (t0), at the end of treatment (t1), and 1 year after completion of treatment (t2). Furthermore, psychosocial variables were documented using questionnaires for parents and children. The mean BMI-SDS (body mass index standard deviation score) reduction at t1 was -0.27 and 1 year later at t2 was -0.23 (per protocol analysis; intention to treat: t1=-0.24; t2=-0.06). Psychological health and quality of life, which were markedly impaired at the beginning, improved. However, physical activity, media consumption, and nutrition remained basically unchanged. A reduction in weight is associated with an improvement in cardiovascular risk profiles, and long-term behavior changes are possible. However, the institutions differed considerably in the percentage of follow-up examinations and in the weight reduction accomplished.