The prevalence of malnutrition in hospitalized patients at surgical, medical and gerontological departments is 40 to 50%. In hospitalized patients above 65 years the prevalence of protein-energy malnutrition (PEM) is even higher and reaches as much s 65%. This mere malnutrition is associated with an increased mortality and morbidity. The interrelationship holds - every chronic disease leads to malnutrition and inadequate nutrition leads to clinically latent or manifest disease. If old people are not admitted to hospital in a state of malnutrition, the nutritional disorder may develop very rapidly during the hospital stay. Even in the course of a brief hospitalization the nutritional status can markedly deteriorate. Wasting and associated functional disorders are in the majority of these patients the results of the catabolic effect of chronic disease and ageing. Loss of weight cannot be separated from disease and we must take it as one of the symptoms suggesting a high risk of death. Although the mutual relationship of undernutrition and adverse prognosis was proved in old people we cannot conclude automatically, that nutritional support will always improve the patient’s prognosis. We have to keep in mind that old age is inevitably associated with deterioration of bodily functions and general wasting. It is most important to keep in mind various nutritional disorders, to identify them in time, or even better, to prevent them. Old people may benefit from various dietary supplements. Only few need artificial nutrition, but those who need it should always get it.

        Key words: malnutrition - body mass index (BMI) - protein energy malnutrition (PEM) - sarcopenia - REE = rest energy expenditure - cachexia - marasmus - old age - nutritional support