Objectives: To evaluate the acceptance of a multinutrient liquid nutrition supplement in psycho-geriatric nursing home patients and the effect on weight, plasma nutrients and activities of daily life. Design: Double-blind, placebo-controlled 12-week intervention study. Setting: Two nursing homes in Boxtel, The Netherlands. Subjects: Forty-two (body mass index (BMI) <23 kg/m2 for men or <25 kg/m2 for women) psycho-geriatric nursing home patients aged 60 y or over. Interventions: Provision with a complete micronutrient-enriched liquid nutrition supplement of 125 ml and 0.6 MJ (135 kcal) or placebo twice daily during daytime between main meals. Study parameters were assessed at 0, 6 and 12 weeks. Main Outcome for Measures: Weight, Barthel index of daily activities, several plasma values (albumin, C-reactive protein (CRP), homocysteine, thiamine, thiamine diphosphate (TDF), vitamin B6, vitamin B12, folic acid, vitamin D), bowel function. Results: The supplement was well accepted. Thirty-five patients completed the intervention period (16 control group; 19 supplement group). Baseline daily nutrient intake was low. A statistically significant improvement was observed for body weight (difference between groups 2.2 kg, P=0.03), and homocysteine, vitamin B1, TDF, vitamin B6, vitamin B12, folate and vitamin D in the supplement group compared to the placebo group. No significant difference was observed in the Barthel index (mean difference -0.3±1.1 for both groups). No difference in occurrence of diarrhoea was observed. Conclusions: The study shows that nutritional supplementation is well accepted and can improve the nutritional status of psycho-geriatric nursing home patients.