Alzheimer's disease (AD) is a leading cause of disability in the elderly, leading to a high burden on caregivers and costs to society. This article describes the current level of data availability regarding the costs of AD in Europe, summarizes and compares findings from previous studies in different countries, and discusses the applicability of available data for modelling purposes. A literature review was conducted for papers in any language reporting data on costs of care for patients with diagnosed dementia or possible/probable AD. Only papers reporting patient-level data on costs were included. A total of 16 studies were identified: from the Nordic region (4), the UK (3), Spain (3), France (2), Italy (2), Belgium (1) and Germany (1). There is large variation in total cost estimates, depending on, for example, differences in study methodology, setting, type and severity of patients included, range of costs assessed and the choice of principle for valuing informal care. The median value for total annual care costs in all studies was Euro28 000 (range Euro6614-Euro64 426) [year 2005 values]. Few studies assessed aspects of disease severity other than cognitive function. The costs of AD in Europe are substantial and increase with disease severity. Methodological differences between studies make comparison across countries and healthcare systems difficult, and there is a need to standardize methods for assessing and valuing informal care. Patient-level information on resource use is required to analyse determinants of care costs and predict the impact of therapeutic interventions. More data are needed to support future economic evaluations of therapies for AD.