Objective: It is generally thought that causes of undernutrition are multifactorial, but there are limited quantitative studies performed. We therefore examined a wide range of potential factors associated with undernutrition in communitydwelling older adults. Design: Cross-sectional study. Setting: Community-dwelling older adults (≥65 years) receiving home care in the Netherlands. Subjects: Data on potential factors associated with (risk of) undernutrition were collected among 300 older adults. Nutritional status was assessed by the SNAQ 65 + instrument. Undernutrition was defined as mid-upper arm circumference <25 cm or unintentional weight loss of ≥4 kg in 6 months. Being at risk of undernutrition was defined as having poor appetite and inability to walk up and down stairs of fifteen steps, without resting. Results: Of all participants, ninety-two (31·7 %) were undernourished and twentyfour (8·0 %) were at risk of undernutrition. Based on multivariate logistic regression analyses, the statistically significant factors associated with (risk of) undernutrition (P < 0·05) were: unable to go outside (OR = 5·39), intestinal problems (OR = 2·88), smoking (OR = 2·56), osteoporosis (OR = 2·46), eating fewer than three snacks daily (OR = 2·61), dependency in activities of daily living (OR = 1·21), physical inactivity (OR = 2·01), nausea (OR = 2·50) and cancer (OR = 2·84); a borderline significant factor was depression symptoms (OR = 1·83, P = 0·053). Conclusions: The study suggests that (risk of) undernutrition is a multifactorial problem and that associated factors can be found in several domains. These findings may support the development of intervention trials for the prevention and treatment of undernutrition in community-dwelling older adults. Keywords Mid-upper arm circumferenceWeight loss Cross-sectional Older adults Community-dwellingIn older adults, undernutrition or protein-energy malnutrition is a commonly reported and worldwide health problem (1) , but there is considerable variety in the reported prevalence rates due to different assessment methods (2,3) . When based on low mid-upper arm circumference (MUAC < 25 cm) and/or unintentional weight loss of ≥4 kg in 6 months, the prevalence of undernutrition in community-dwelling older adults is estimated to be between 11 and 35 % (4) . The prevalence of (risk of) undernutrition, defined as poor appetite in the previous week in combination with difficulty climbing stairs, is estimated between 2 and 9 % (4) . Due to the ageing population, increasing pressure on health-care systems initiates a shift in care from the institutional setting to the community. For this reason, prevention and treatment of undernutrition in community-dwelling older adults is essential.In order to prevent and treat undernutrition in community-dwelling older adults, clear insight into the primary and secondary factors associated with undernutrition is needed. In previous studies undernutrition in older adults was associated with poor health outcomes including decreased functionali...