Literature data and own experience of nutritional support in oncology has been analyzed. Nutritional support is an integral part of the management of cancer patients. Diagnosis of nutritional deficiencies is important, with an accent on early detection of muscle loss and severely malnourished patients. The main methods of nutritional support are oral nutritional supplements, enteral and parenteral nutrition, as well as dietary advice and maintenance of physical activity. Oral nutrition should always be used in the absence of absolute contraindications. The effectiveness and indications of prehabilitation measures require further study, but now it is possible to single out a category of patients in whom they can be fully implemented. It can be cases requiring neoadjuvant chemotherapy.