Objectives: High rates of malnutrition have been reported in the older hospitalized patient population. this is recognised to impact on patient outcomes and health costs. this study aimed to assess the impact of nutrition screening and intervention on these parameters. Design: randomised controlled prospective study. Setting: the study was performed in the acute geriatric medicine wards of the prince of Wales Hospital, Sydney australia. Participants: all patients admitted to these wards under a geriatrician with an expected length of stay of at least 72 hours were considered for the study. Intervention: patients were screened on admission for malnutrition using the Mini nutritional assessment (Mna) tool and randomly assigned to control or intervention groups. intervention patients were immediately commenced on a malnutrition care plan (MCp). Control patients were only commenced on a MCp if referred by clinical staff. Measurements: length of stay (loS), weight change and frequency of readmission to hospital were compared between the groups. Results: 143 patients were screened. 119 were identified as malnourished (Mn) or at risk of malnutrition (ar). overall loS was not different between the two groups (control v. intervention: 13.4 ± 1.3days v. 12.5 ± 1.2 days, p=0.64). However there was a significant decrease in loS in the Mn (control v. intervention: 19.5 ± 3days v. 10.6 ± 1.6 days, p=0.013) and a trend to reduced readmissions. there was no difference in weight change over admission between the groups. Without screening, clinical staff identified only a small proportion of malnourished patients (35% of Mn and 20% of ar). Conclusions: Malnutrition in the older hospital population is common. Malnutrition screening on hospital admission facilitated targeted nutrition intervention, however length of stay and representations were only reduced in older malnourished patients with an Mna score less than 17.