Malnutrition is a common problem in cancer patients, associated with an increased risk of complications and a reduced response to treatment resulting to a poorer outcome. Both age and oncological disease can affect the state of nutrition in multiple ways. In elderly, malnutrition can be affected either directly by the tumour process (local effect, host response to the tumour ...), by the adverse effects of the treatment, and by the impact of several psychosociological and physiological factors due to aging. Prophylactic interventions in all these stages should therefore be done, addressing the specific needs of this patients group, and suggesting the systematic use of an out-patient screening tool (MNA). Assessing and modifying nutrition must be an integral part of the treatment.