A collaborative study involving nutrition screening of 3,047 patients (excluding 125 pregnant women) at admission to 33 hospitals in and around the greater Chicago area was carried out to identify patients at nutritional risk. Information on sex, age, admitting diagnosis, serum albumin, hemoglobin, total lymphocyte count, and height and weight was collected from the medical chart within 48 hours of admission. Nutrition screening could not be completed for a larger number of patients (60%) because data at admission were not available. Of the remaining 40% of patients, more than 50% had below normal values for one or more of the variables studied: serum albumin, hemoglobin, and total lymphocyte count. A large number of the patients (40%) also were considered at nutritional risk as judged by the criteria of weight/height (measured only). Early nutrition intervention for high-risk patients cannot be implemented, nor can the efficacy of nutrition services be evaluated, unless nutrition screening is carried out on patients at admission.