Anxiety disorders (panic disorder/agoraphobia, generalized anxiety disorder, social phobia, and specific phobias) are the most common mental illnesses. For example, the 12-month prevalence of panic disorder/agoraphobia is 6%. This guideline is based on controlled trials of psychotherapy and pharmacotherapy, retrieved by a systematic search for original articles that were published up to 1 July 2013. Experts from 20 specialty societies and other organizations evaluated the evidence for each treatment option from all available randomized clinical trials and from a synthesis of the recommendations of already existing international and German guidelines. 403 randomized controlled trials were evaluated. It was concluded that anxiety disorders should be treated with psychotherapy, psychopharmacological drugs, or both. Response rates to initial treatment vary from 45% to 65%. Cognitive behavioral therapy is supported by higher-level evidence than any other psychotherapeutic technique. Psychodynamic therapy is recommended as a second-line treatment. Among anxiolytic drugs, the agents of first choice are selective serotonin reuptake inhibitors and serotoninnorepinephrine reuptake inhibitors. The patient's preference should be considered in the choice of treatment. Drug treatment should be continued for 6 to 12 months after remission. If psychotherapy or drug treatment is not adequately effective, then the treatment should be switched to the other form, or to a combination of both. The large amount of data now available from randomized controlled trials permits the formulation of robust evidence-based recommendations for the treatment of anxiety disorders. Future work should more closely address the necessary duration of psychotherapy and the efficacy of combined psychotherapy and drug treatment.