OBJECTIVES: To analyse the economic impact of one-year healthcare and non-healthcare resources utilization by patients with Alzheimer disease (AD) under usual medical practice conditions in Spain. METHODS: A one-year, prospective, naturalistic, multicentre cohort study was designed to recruit treated patients with mild, moderate to severe and severe AD according to CDR: the ECO study. Healthcare resources included all kind of medical visits, drugs and concomitant treatments, complementary tests, institutionalization and home-nursing facilities’ use. Non-healthcare resources included inventory materials, consumables, professional and non-professional carers’ time of care and supervision. Results were analysed according to patients´ socio-demographic data, degree of AD (CDR; MMSE and BDRS), overall health status (HUI3), and to variables inherent to the main carer including hours of care and supervision and health status (HUI3) and stress (Zarit). RESULTS: A total of 560 patients with possible/probable AD by DSM-IV-NINCDS-ADRDA criteria were included in the study; 68% women, 77±6 years old, 29% treatment naïve. Monthly mean cost was €1,078 (€12,936 patient/ year), increasing by 9.4% at the end of the study from a baseline cost of €993. By components, non-healthcare costs (€760, 71% of total cost) decreased €7 (0.8%) at the end of the year, while healthcare costs grew €101/month (43.9%), mainly driven by the cost of drugs, nursing home utilization and institutionalization. The 82% of the overall cost (€884) was not financed by Social Security, and the majority of this cost corresponded to caregiver associated cost (salaries and productivity lost). The caregiver economical burden represents 68% of the overall cost-of-illness. CONCLUSIONS: Monthly overall mean cost of AD was high in Spain (€1078), More than 80% of the cost-of-illness is funded by the own patient family, adding an economical burden to the suffering of these families.