BMI is commonly used indicator of malnutrition and 18.5-24.9 kg/m(2) is generally regarded optimal. However, there is an ongoing debate on ideal range for elderly. BMI cut-off values vary also between ethnic groups. We aimed to investigate relationships between BMI, functional status and malnutrition in elderly living in a nursing home in Turkey. BMIs of 254 residents were calculated. Chronic diseases and currently used drugs were noted. Functional status was evaluated with Katz-activities-of-daily-living (ADL) and Lawton-instrumental-activities-of-daily-living (IADL). Nutritional assessment was performed by Mini-Nutritional-Assessment (MNA) test. Mean age was 75.2 +/- 8.2 years. Subjects were classified into 4 groups as BMI < 18.5, 18.5-24.9, 25-29.9, and >= 30.0 kg/m(2). ADL scores and IADL scores were higher in higher BMI groups. There were no differences in terms of age-number of chronic diseases. Even in BMI >= 35 kg/m(2) residents, ADL was significantly higher than 25-34.9 kg/m(2) residents. BMI was significantly correlated with ADL and IADL scores. In Groups 3 and 4, there were 22.2% and 9.1% residents without normal nutrition, respectively. Better functional status was associated with higher BMI values even in BMIs >= 30 kg/m(2). In elderly, relative high rates of undernutrition may be present in BMIs regarded as overweight or obese. (C) 2011 Elsevier Ireland Ltd. All rights reserved.