Diet therapy and clinical nutrition have a significant place in the treatment of patients with inflammatory bowel disease (IBD). Nutritional support is an important component of medical therapy in patients with IBD, and in-cludes the prevention and treatment of all forms of malnutrition. Confirmed malnutrition in patients with in-flammatory bowel disease should be treated adequately as it exacerbates prognosis, degree of complications, mortality and quality of life of a patient. Enteral nutrition is an extremely important part of nutritional therapy in inflammatory bowel diseases, and in some situations it has the meaning of primary therapy. Parenteral nutri-tion has its place in nutrition therapy of inflammatory bowel disease, both in acute and chronic treatment of patients with short bowel syndrome. Representatives of the Croatian Society of Clinical Nutrition Croatian Medical Association, Croatian Society of Mucosal Immunology Croatian Medical Association, Croatian Society of Gastroenterology and Croatian Society of Nutritionists and Dietitians participated in the development of these guidelines. They are evidence-based, according to the GRADE (Grading of Recommendations, Assess-ment, Development and Evaluation) system which, with the strength of evidence, also describes the level of recommendation. The basic conclusions of these guidelines relate to the assessment of malnutrition in this group of patients, the determination of nutritional needs, the replacement of key nutrients and pharmaconutrients, the application of various artificial nutrition modalities and the specificities of perioperative nutrition.