Costs of dementia care constitute a great part of the total costs of care for elderly. Because the prevalence of dementia is linked to increasing age, and the number of the oldest old is rising, the costs of dementia care will increase considerably in the forthcoming decades. In this review, research describing costs of dementia care has been analysed and classified. The available database in this field is small, though expanding, and the methodological problems are obvious. Differences between countries, and between different periods of time, are difficult to analyse due to different methods of financing and organizing care. The main result of the present study is that the costs of dementia care differ considerably in the literature. One important reason for this variability is that the number of included cost categories vary, leading to a wide range of costs. Unpaid informal care forms a major part of the total costs, but the theory of costing informal care is complicated.