The paper presents current views on the diagnosis and medical treatment of Crohn's disease (CD). It considers the present-day principles in the classification, evaluation of the severity of the disease, and its diagnostic criteria. There are actual medical treatment regimens for CD, regulated by the project of Russian clinical guidelines for the diagnosis and treatment of CD in adults (2013), which were drawn up by leading Russian experts relying on the European evidence-based consensus on the diagnosis and management of CD (2010). Promising treatment options for CD, which affect the key molecules of the pathogenesis of this disease, are considered.