Biologics, usually monoclonal antibodies or fusion proteins, are thought to specifically interfere with immunopathogenesis of chronic inflammatory diseases. In order to test these substances also in children and adolescents, financial incentives for manufacturers were created and classification of chronic inflammatory diseases and definition of disease activity, improvement, relapse and remission were established and large international research cooperation projects were founded. A selective literature search was carried out for treatment of chronic inflammatory diseases in children and adolescents with biologics including current guidelines. Only 7 out of 18 prescribed biologics have been approved for children and mostly within narrow limits. The evidence for efficacy is based on four randomized double blind placebo-controlled studies, seven withdrawal studies and seven observational studies. In spite of the limited evidence in comparison to their use in adult patients these substances are broadly used worldwide and have enlarged and substantially improved the therapeutic choices in children when conventional treatment failed or proved to be toxic. Severe adverse events including infections occasionally occur (0.01-0.03 events per patient year) but the rate of malignancies is not obviously increased; however, only two thirds of patients respond to treatment. Improvement is often incomplete, some patients deteriorate and definite termination of drug treatment is possible in only a few patients. As the prescription of biologics has become an important issue of treatment but is based on insufficient evidence data, further studies are necessary in children and adolescents with diseases, such as juvenile idiopathic arthritis, Crohn's disease, ulcerative colitis and inherited fever syndromes. As many drugs are available these studies can be conducted against verum.