Crohn's disease is a disorder of unknown etiology and complicated pathogenesis. A substantial amount of evidence has accumulated recently and has been applied to clinical practice. The present guidelines were developed based on recent evidence and the formal consensus of experts relevant to this disease. Here we provide an overview of these guidelines, as follows. Target disease: Crohn's disease Users: Clinical practitioners in internal medicine, surgery, gastroenterology, and general practice Purpose: To provide appropriate clinical indicators to practitioners Scope of clinical indicators: Concept of Crohn's disease, epidemiology, classifications, diagnosis, treatment, follow up, and special situations Intervention: Diagnosis (interview, physical examination, clinical laboratory tests, imaging, and pathology) and treatment (lifestyle guidance, drug therapy, nutritional therapy, surgery, etc.) Outcome assessment: Attenuation of symptoms, induction and maintenance of remission, imaging findings, quality of life (QOL), prevention of complications and harm of therapy Methods for developing these guidelines: Described in the text Basis of recommendations: Integration of evidence level and consensus of experts Cost-benefit analysis: Not implemented Evaluation of effectiveness: Yet to be confirmed Status of guidelines: Updated version of the first Guidelines published in 2010 Publication sources: Printed publication available and electronic information in preparation Patient information: Not available Date of publication: October 2011 These guidelines were intended primarily to be used by practitioners in Japan, and the goal of these guidelines is to improve the outcomes of patients with Crohn's disease.