The purpose of this study was to describe and compare demographical, sociomedical and physical characteristics between protein-energy malnourished and non-malnourished geriatric patients on admission. According to the International Statistical Classification of Diseases, 104 malnourished patients were age-, gender- and diagnosis-matched with 104 non-malnourished patients. Data were collected from patients' medical records. The patient's condition was assessed by a modified Norton scale on admission. No differences were seen in marital status, type of dwelling, previous need for help service, residence before admission, and dependence on assistance with ADL function. The malnourished patients had a greater consumption of diuretics (47%; P less than 0.05) and a lower consumption of analgesics (29%; P less than 0.05) than the non-malnourished patients (33% and 42% respectively). In the malnourished group, impaired conditions in activity (83%; P less than 0.05), and general physical condition (78%; P less than 0.01) were observed compared to the non-malnourished group (69% and 60% respectively). The malnourished patients had less sufficient food intake (41% vs 21%; P less than 0.01) and fluid intake (25% vs 10%; P less than 0.01) than non-malnourished patients. This study indicates that demographical characteristics and primary ADL-functions are of minor importance for the development of protein-energy malnutrition in geriatric patients. Observation of the patients' physical condition and drug consumption seemed more important on admission.