Nutritional status of patients significantly affects the outcome of surgical treatment, whether it's about being obese or malnutrition with loss of muscle mass. Inadequate nutritional support in the perioperative period compromises surgical procedures even in patients who are adequately nourished. In this paper, particular attention was paid to malnourished patients, and their incidence in population hospitalized in surgical wards can be high up to 30%. Special emphasis was paid to the appropriateness of preoperative fasting and to the acceptance of new knowledge in this area of treatment. The aim of this working group was to make guidelines for perioperative nutritional support with different modalities of enteral nutrition. The development of these guidelines was attended by representatives of Croatian Medical Association: Croatian Society for Digestive Surgery, Croatian Society for Clinical Nutrition, Croatian Society of Surgery, Croatian Society for Endoscopic Surgery, Croatian Trauma Society and the Croatian Society of Anesthesiology and Intensive Care. The guidelines are designed as a set of questions that arise daily in clinical practice when preparing patients for surgery and after the surgical treatment, which relate to the assessment of nutritional status, perioperative nutritional support, duration of preoperative fasting period and the selection of food intake route. Assessment of nutritional status and the use of different modes of enteral nutrition should enter into standard protocols of diagnosis and treatment in the Croatian hospitals.