BACKGROUND: Little account has been taken of quality of life (QoL) among family carers of adults with an intellectual disability (ID) and family carers of adults with a mental illness (MI), particularly the female ageing carers' perceived stigma. We explore whether there are differences in the significant predictors of female ageing family carers' QoL between family carers of adults with ID and family carers of adults with MI and aim to examine the effect of these differences in stigma on carer QoL between the two groups.