BACKGROUND Mental illness is common, under detected and often poorly managed in residential aged care facilities. These concerns have achieved greater prominence as the worldwide population ages. Over 80% of people in nursing home care fulfill criteria for one or more psychiatric disorders in an environment that often presents significant difficulties for assessment and treatment. OBJECTIVE This article aims to provide an overview of the important mental health issues involved in providing medical care for patients with behavioural and psychological problems in residential aged care facilities. CONCLUSIONS Recent developments in education and training, service development and assessment and treatment strategies show some promise of improving the outcome for aged care residents with mental health problems. This is of especial relevance for primary care physicians who continue to provide the bulk of medical care for this population.