Objective The objective of this article is to study which factors are associated with depression and anxiety in older adults with intellectual disabilities (ID). Methods Depressive and anxiety symptoms were studied in 990 participants with borderline to profound ID, aged50years, using self-report and informant-report screening questionnaires. In 290 participants, major depression and anxiety disorders were assessed with a standardised psychiatric interview. Associations with personal, medical and psychosocial factors, which were collected through questionnaires and participants' medical and psychological records, were studied using multiple logistic regression analysis. Results Increased depressive symptoms were positively associated with increased anxiety symptoms, number of life events during the past year and chronic diseases (heart failure, stroke, chronic obstructive pulmonary disease, coronary artery disease, diabetes mellitus and malignity in the previous 5years) and negatively with instrumental activities of daily living (IADL) abilities. Major depression was positively associated with chronic diseases and negatively with IADL abilities. Increased anxiety symptoms were positively associated with borderline or mild ID and increased depressive symptoms and negatively associated with Down syndrome, epilepsy and social contacts. Anxiety disorders showed no significant associations. Conclusions To develop effective prevention and treatment policies, factors associated with depression and anxiety in older adults with ID should be further examined in longitudinal research. Copyright (c) 2012 John Wiley & Sons, Ltd.