Clinical and epidemiological studies have established that malnutritionis a risk factor for infection in patients being submitted to surgery. To date no study has been carried out to establish the association between the nutritional condition and the incidence of hospital-acquired infections in patients in the medical area. We study the incidence of hospital-acquired infections in the elderly in an attempt to determine the rate of this infection and its association with protein-calorie malnutrition. Another aim of this study has been to determine the predictive value of the parameters used to evaluate the patient's state of nutrition and immunity. We included 240 patients over 64 years old, 118 males and 122 females, admitted to the medical area of a general hospital. The nutritional and immunity condition of the patients was evaluated through determinations of weight, height, body mass index, hypoalbuminemia and total lymphocyte count. The psichophisical degree of dependence was evaluated through of Norton scale. The details on the hospital infections came from a clinical and microbiological follow-up of patients, in accordance with the criteria of the Centers for Disease Control of Atlanta. The frequency of protein-calorie malnutrition was 12.5% and the accumulated incidence of hospital-acquired infections was 19.6%. Functional incapacity of the elderly prior to hospitalization (odds ratio,4.70; 95% CI: 1.1-19.0) as well as the presence of certain extrinsicrisk factors (odds ratio, 2.35; 95% CI: 1.1-5.1) were, in addition to hypoalbuminemia (odds ratio, 3.60; 95% CI: 1.3-10.2) and lymphocytopenia(odds ratio, 2.67; 95% CI: 1.3-5.7), the independent variables that showed the most significant association with the incidence of hospital-acquired infections. The nutritional parameters associated with the immune system determinedgreater risk of hospital-acquired infections among elderly patients admitted to the medical area of a hospital. The initial evaluation of elderly patients hospitalitzed in accordance whit the psychophysical degree of dependence based on the Norton scale is useful to evaluate those patients who were at greater risk for hospital infections.