OBJECTIVE The aim of this study was to describe changes in the nutritional status of nursing home residents over a period of 1 year and identify factors associated with a decline in nutritional status. BACKGROUND The maintenance of good nutritional status is important for nursing home residents. Therefore, it is essential to identify risk factors that indicate a decline in nutritional status to take early prevention steps. METHODS Secondary data analysis of repeated cross-sectional studies. METHODS Data collection was performed between 2009-2013 using the International Prevalence Measurement of Care Problems questionnaire. Data from three purposively selected nursing homes that included 157 residents were analysed. RESULTS The comparison between baseline data and data collected 1 year later showed that the nutritional status declined in 22·8% of the residents and improved in 6·5% of the cases. The body mass index and changes in the body mass index were significantly different between residents with stable/improved and declined nutritional status. The multivariate logistic regression analysis showed that care dependency, length of stay, changes in body mass index and malnutrition risk at baseline were significantly associated with a decline in nutritional status. CONCLUSIONS This study showed that the baseline risk of malnutrition is the most important risk factor indicating a decline in nutritional status. Therefore, healthcare professionals should identify the malnutrition risk and take action as early as possible.