Psychological distress can lead to negative consequences affecting the quality of life of older adults living in long-term care centres. The goal of this study was to determine the prevalence of symptoms of psychological distress and their associated factors among these residents. A cross-sectional descriptive study was conducted among 1999 long-term care residents aged 65 and over. Nine hundred and eleven persons (45.6%) displayed at least one symptom of psychological distress either at one time or more in the week preceding data collection, and 22.4% were identified as psychologically distressed. Multivariate analysis indicated that psychological distress was associated with disruptive behaviours and benzodiazepine use among women residents, and with insomnia in men residents. In conclusion, when clinicians screen for mental health disorders, they should take into consideration that symptoms of insomnia or disruptive behaviours may mask psychological distress.