To address socioeconomic challenges associated with its increasing prevalence, data are needed on country-level resource use and costs associated with Alzheimer's disease (AD). GERAS is an 18-month observational study being conducted in France, Germany, and the U.K. (with an 18-month extension in France and Germany), aimed at determining resource use and total costs associated with AD, stratified by AD severity at baseline. Resource use information and time spent on informal care by non-professional caregivers was obtained using the Resource Utilization in Dementia instrument. Total baseline societal costs were based on four cost components: patient health care costs, patient social care costs, caregiver health care costs, and caregiver informal care costs. Overall, 1,497 community-dwelling patients with AD were analyzed at baseline. Estimated mean monthly total societal costs per patient at baseline differed significantly between groups with mild, moderate, and moderately severe/severe AD (p < 0.001 in each country): euro $1,418, euro 1,737, and euro 2,453 in France; euro 1,312, euro $2,412, and euro 3,722 in Germany; and euro 1,621, euro 1,836, andeuro 2,784 in the U.K., respectively. All cost components except caregiver health care costs increased with AD severity. Informal caregiver costs were the largest cost component accounting for about half to just over 60% of total societal costs, depending on country and AD severity group. In conclusion, GERAS study baseline results showed that country-specific costs increase with AD severity. Informal care costs formed the greatest proportion of total societal costs, increasing with AD severity independent of costing method. Longitudinal data will provide information on cost trends with disease progression.