Denutrition of cancer patients is a complex phenomenon involving inadequate calorie uptake from anorexia and metabolic disorders. The malignancy itself is the source of excessive energetic expenditure secondary to little known biological disturbances. Several effects of cytostatic drugs also contribute to nutritional imbalance. The need for re-establishing nutritional balance becomes obvious when the detrimental consequences of denutrition (particularly as regards immune defence mechanisms) are borne in mind. Nutritional requirements can be accurately determined by means of repeated simultaneous analysis of simple data. When oral feeding, even supplemented, appears insufficient, artificial feeding is capable of reducing, at least partly, the nutritional deficiency, improving the patient's comfort, lowering the incidence of infections and improving tolerance of cytostatic drugs. The effects of artificial feeding on response to these drugs have not yet been clearly established. Continuous enteral feeding deserves to be revalorized; it should be preferred to parenteral feeding when digestive functions remain satisfactory.