Malnutrition in the hospital is not a new or rare problem, however, it is often unrecognized. In order to determine the baseline nutritional characteristics of recently hospitalized patients, we assessed the nutritional status of all medical in-patients between April and December 1994 in a large hospital in the province of Buenos Aires. One hundred and seventy patients were derived from the Internal Medicine ward and 176 patients from the General Surgery ward. Surgery patients were younger (median: 46 years vs 58 years of the Medicine patients). Among Medicine patients, cardiovascular and respiratory afflictions were the most common (30%), while gastrointestinal disorders were more often seen in Surgical patients (71%). A weight loss of more than 10% (%WL) was found in 12% of the Medicine and Surgery patients and a body mass index (BMI) of less than 19 kg/m2 was observed in about 5% of both groups. Ten percent of the Medicine patients and 14% of the Surgery patients were overweight. A mid-upper arm muscle circumference (MUAMC) less than the fifth percentile was found in 11% of the Medicine patients but in only 3% of the Surgery patients. These results suggest that this population of recently hospitalized patients is at high-risk for medical complications. Therefore, early nutrition assessment and appropriate nutrition intervention are required to improve clinical outcome and help reduce the cost of health care.