Background This survey study aims to examine the prevalence and factors associated with depressive symptoms among primary older female family carers of adults with intellectual disabilities (ID).Method In total, 350 female family carers aged 55 and older took part and completed the interview in their homes. The survey package contained standardised scales to assess carer self-reported depressive symptoms, social support, caregiving burden and disease and health, as well as adult and carer sociodemographic information. Multiple linear regressions were used to identify the factors associated with high depressive symptoms in carers.Results Between 64% and 72% of these carers were classified as having high depressive symptoms. The factors associated with carer self-reported depressive symptoms were carer physical health, social support and caregiving burden; overall, the carer self-reported physical health was a stronger factor associated with depressive symptoms than their physical disease status. The level of the adult with ID's behavioural functioning and the carer age, marital status, employment status, education level and the family income level were not significantly associated with carer depressive symptoms.Conclusions The factors identified in this study as correlating with self-reported depressive symptoms suggest that researchers and mental health professionals should collaborate to help improve the physical health and social support networks of the most vulnerable older female family carers. This should reduce depressive symptoms directly among this high-risk group.