Malnutrition has been identified as affecting patient outcome. The purpose of this study was to correlate the nutritional status of hospitalized patients with their morbidity, mortality, length of hospital stay and costs. The patients were nutritionally assessed within the first 72 h of hospital admission. The patients' charts were surveyed on the incidence of complications and mortality. Hospital costs were calculated based on economic tables used by insurance companies. Multivariate logistic regression analysis and the Cox regression model were used to identify possible confounding factors. A P<0.05 was considered statistically significant. The mean age was 50.6+/-17.3 years with 50.2% being male. The incidence of complications in the malnourished was 27.0% [Relative risk (RR)=1.60]. Mortality in the malnourished patients was 12.4% vs 4.7% in the well nourished (RR = 2.63). Malnourished patients stayed in the hospital for 16.7+/-24.5 days vs 10.1+/-11.7 days in the nourished. Hospital costs in malnourished patients were increased up to 308.9%. It was concluded that malnutrition, as analyzed by a multivariate logistic regression model, is an independent risk factor impacting on higher complications and increased mortality, length of hospital stay and costs.