Objective: To determine the extent to which patients with objective signs of malnutrition had been diagnosed as such by physicians and the diagnosis documented in the medical record. Design: Cross-sectional. Subjects: All non-critically ill patients (n = 121) aged 70 years or older admitted to an Oslo hospital during a 3-week period. Methods: Compared problem list and other elements of the medical record with observations of height, weight, triceps skinfold, midarm circumference, and arm-muscle circumference made on first weekday in hospital. Serum albumin available on 66 subjects. Main Results: Nine patients had weight/height ratios below 60% of normal, 16 patients between 60% and 75%, and 41 patients between 74% and 90% of normal. Of these 66 patients, only 24 were recognized as malnourished on admission, only five received nutritional support, and none was diagnosed as having malnutrition at the time of discharge. Conclusions: Malnutrition is underdiagnosed and under-treated. The consequences of this are likely to be deleterious to health.