The nutritional state of 309 geriatric patients in a medical clinic was determined with the following parameters: Weight/height index, triceps skin fold, arm muscle circumference, creatinine/height index, albumins, prealbumin, transferrin and cholinesterase. Using these parameters we found that 54,4% of these patients were suffering from malnutrition (27,8% marasmus, 9,4% kwashiorkor-like syndrome, 17,2% marasmic kwashiorkor). Triceps skin fold, arm muscle circumference and creatinine/height index were the most precise parameters to confirm marasmus. Prealbumin and cholinesterase are especially recommended to determine acute protein deficiency, albumin to confirm chronic protein deficiency. It was also possible to demonstrate the deleterious effect of malnutrition on the immunological system of the patient through determination of the absolute lymphocyte count in peripheral blood and intracutaneous testing with streptokinase-dornase, mumps skin test antigen and candida vaccine.