Nutrition is a key element in geriatric health and is important for functional ability. The present study examined the functional status-predictive ability of the Mini-Nutritional Assessment (MNA). We analysed the dataset of the ‘Survey of Health and Living Status of the Elderly in Taiwan’, a population-based study conducted by the Bureau of Health Promotion of Taiwan. Study subjects ( ≥ 65 years old) who completed both the 1999 and 2003 surveys were rated with the long form and short form of the MNA at baseline and with the Activities of Daily Living (ADL) and the Instrument Activities of Daily Living (IADL) scales 4 years later (end-point). The ability of the MNA to predict ADL or IADL dependency was evaluated with logistic regression models. The results showed that the elderly who were rated malnourished or at risk of malnutrition at baseline generally had significantly higher ADL or IADL scores 4 years later. Lower baseline MNA scores also predicted a greater risk of ADL or IADL dependency. These associations exist even among the elderly who were free of ADL or IADL dependency at baseline. The results clearly indicate that the MNA is able to predict ADL and IADL dependency (in addition to rating current nutritional status) of the elderly. The MNA, especially the short form, should be a valuable tool for identifying elderly at risk of functional decline and/or malnutrition in clinical practice or community programmes.