Background & aims: To examine the effect of malnutrition on clinical outcomes and healthcare resource use from initial diagnosis by a general practitioner (GP) in the UK. Methods: 1000 records of malnourished patients were randomly selected from The Health Improvement Network database and matched with a sample of 996 patients' records with no previous history of malnutrition. Patients' outcomes and resource use were quantified for six months following diagnosis. Results: Malnourished patients utilised significantly more healthcare resources (e.g. 18.90 versus 9.12 GP consultations; p < 0.001, and 13% versus 5% were hospitalised; p < 0.05). The six-monthly cost of managing the malnourished and non-malnourished group was 1753 pound and 750 pound per patient respectively, generating an incremental cost of care following a diagnosis of malnutrition of 1003 per patient. Thirteen percent and 2% of patients died in the malnourished and non-malnourished group respectively (p < 0.001). Independent predictors of mortality were: malnutrition (OR: 7.70); age (per 10 years) (OR: 10.46); and the Charlson Comorbidity Index Score (per unit score) (OR: 1.24). Conclusion: The healthcare cost of managing malnourished patients was more than twice that of managing non-malnourished patients, due to increased use of healthcare resources. After adjusting for age and comorbidity, malnutrition remained an independent predictor of mortality. (C) 2011 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.