OBJECTIVES To describe the nutritional status of older persons living at home, to investigate factors of importance for nutritional status, and to describe possible relationships between nutritional status and health-related quality of life (HRQoL). DESIGN A longitudinal study using data from older persons born between 1916 and 1925. Data were collected at three occasions separated by four-year intervals. SETTING Data collection was carried out in the participants' own homes. An experimenter administered all tests and conducted the interviews. PARTICIPANTS A randomized selection from the Swedish Twin Register included 258 persons, all still living at home. MEASUREMENTS Nutritional status was assessed using the Mini Nutritional Assessment (MNA), cognitive function using the Mini-Mental State Examination (MMSE) and HRQoL using the Nottingham Health Profile (NHP). Questions covering physical, psychological and social factors that may have an impact on nutritional status were also posed. RESULTS Approximately 17% of participants were assessed as being at risk for malnutrition or as being malnourished. Cognitive impairment, reduced perceived health, recent hospital stay and receiving meals-on-wheels were factors associated with being at risk for malnutrition. CONCLUSION Being at risk for malnutrition is common in older persons living at home, and many factors related to frailty increase this risk in later life. Making use of knowledge of these factors when giving care to older persons may be important in preventing nutritional problems.