Langerhans Cell Histiocytosis (LCH) is an orphan disease of clonal dendritic cells which may affect any organ of the body. Most of the knowledge about the diagnosis and therapy is based on pedriatic studies. Adult LCH patients are often evaluated by physicians who focus on only the most obviously affected organ without sufficient evaluation of other systems, resulting in patients being underdiagnosed and/or incompletely staged. Furthermore they may be treated with pediatric-based therapies which are less effective and sometimes more toxic for adults. The published literature on adult LCH cases lacks a comprehensive discussion on the differences between pediatric and adult patients and there are no recommendations for evaluation and comparative therapies. In order to fill this void, a number of experts in this field cooperated to develop the first recommendations for management of adult patients with LCH. Key questions were selected according to the clinical relevance focusing on diagnostic work up, therapy, and follow up. Based on the available literature up to December 2012, recommendations were established, drafts were commented by the entire group, and redrafted by the executive editor. The quality of evidence of the recommendations is predominantly attributed to the level of expert opinion. Final agreement was by consensus.