for the guideline group* T he scientists and physicians involved in research on Lyme neuroborreliosis agree that this disease can be reliably diagnosed and permanently stopped with a two-to three-week course of antibiotic treatment. There nonetheless exists a widespread fear that Lyme disease (as it is also called) can lead to a wide variety of nonspecific symptoms, such as chronic pain, fatigue, and difficulty concentrating, despite antibiotic treatment. This view often leads to repeated courses of antibiotic treatment being given for several months at a time, sometimes with serious adverse effects; there have even been a few deaths (e1-e3). The objective of the S3 guideline on Lyme neuroborreliosis issued by the German Society of Neurology (Deutsche Gesellschaft für Neurologie) is, therefore, to provide clear recommendations on the diagnosis and treatment of this disease which are based on a structured evidence and consensus process. Epidemiology Lyme borreliosis is an infectious disease that manifests itself primarily on the skin, in the nervous system, and in the joints. Five species of Borrelia burgdorferi that are pathogenic for human beings have been identified as the responsible organisms in Europe; they are transmitted by the bite of Ixodes ricinus, a species of hard tick. The number of new cases in Germany each year is variably estimated from 60 000 to over 200 000 (e4, e5), in the absence of precise figures. The seroprevalence of Borrelia-specific antibodies in healthy persons ranges from 5% to 20%, depending on their age and place of residence (e6-e8). According to German surveys, tick bites lead to seroconversion in 2.6%-5.6% of cases, and to overt disease in 0.3-1.4% (e9-e11). Method The first step in the creation of the guideline was a search for, and an assessment of, already existing guidelines on the subject, of which eight were found. Structured evaluation revealed that all of them had low quality scores, with the result that none of their recommendations could be adopted without further investigation (1). To assess the various proposed modes of antibiotic treatment, systematic literature searches were carried out in three databases: • Medline (via Ovid), • Embase (via Scopus), • and the Cochrane Central Register of Controlled Trials. Each included study was assessed in structured fashion (2, 3). The results for all of the included Summary Background: The new German S3 guideline on Lyme neuroborreliosis is intended to provide physicians with scientifically based information and recommendations on the diagnosis and treatment of this disease. Methods: The scientific literature was systematically searched and the retrieved publications were assessed at the German Cochrane Center (Deutsches Cochrane Zentrum) in Freiburg in the 12 months beginning in March 2014. In addition to the main search terms "Lyme disease," "neuroborreliosis," "Borrelia," and "Bannwarth," 28 further terms relating to neurological manifestations of the disease were used for the search in the Medline and Embase databases and in...