Dementia is a costly condition and one that differs from other conditions in the significant cost burden placed on informal caregivers. The aim of this analysis was to estimate the economic and social costs of dementia in Ireland in 2010. With an estimate of 41,470 people with dementia, the total baseline annual cost was found to be over €1.69 billion, 48% of which was attributable to the opportunity cost of informal care provided by family and friends and 43% to residential care. Due to the impact of demographic ageing in the coming decades and the expected increase in the number of people with dementia, family caregivers and the general health and social care system will come under increasing pressure to provide adequate levels of care. Without a significant increase in the amount of resources devoted to dementia, it is unclear how the system will cope in the future.