Background: The GERAS II study aimed to assess societal costs and resource use associated with Alzheimer's disease (AD) for patients and their primary caregivers in Italy and Spain, stratified for different severity stages of AD at baseline. This report presents baseline results for Italy.; Design: GERAS II was a prospective, multicentre, observational study of routine care in AD.; Setting: Community-dwelling patients attending specialist secondary care centres (memory clinics/Alzheimer's Evaluation Units) and their primary informal caregivers were recruited into the study.; Participants: Patients were aged ≥55 years, presented within the normal course of care, had a diagnosis of probable AD and a Mini-Mental State Examination (MMSE) score of ≤26. Patients and caregivers were stratified according to patient AD dementia severity at baseline: mild, MMSE score 21-26; moderate, MMSE score 15-20; or moderately severe/severe, MMSE score <15.; Measurements: Data collected for patients and caregivers included demographics/clinical characteristics; current medication; patient cognitive, functional and behavioural assessments; patient and caregiver health-related quality of life (HRQoL); and patient and caregiver resource use. The costs associated with the resources used were calculated. Costs were broken down into patient healthcare costs, patient social care costs and caregiver informal care costs.; Results: Of 198 patients enrolled from Italy, 29 (15%) had mild AD dementia, 80 (40%) had moderate AD dementia, and 89 (45%) had moderately severe/severe AD dementia. Patient and caregiver characteristics showed some differences between AD dementia severity groups; for example, a numerically higher proportion of patients with mild and moderately severe/severe AD dementia were taking memantine compared with those with moderate AD dementia. Patient functioning and behavioural and psychological symptoms worsened with increasing AD dementia severity (p<0.05 between groups for all measures). No significant difference between the disease severity groups was observed in patient HRQoL, and there was no clear pattern in resource use. However, all measures of caregiver time spent helping the patient differed significantly between groups (p<0.05) and were highest in patients with moderately severe/severe AD dementia. Mean (standard deviation) total monthly societal costs per patient (2013 values) were €1850 (1901), €1552 (1322) and €2728 (2184) for patients with mild, moderate and moderately severe/severe AD dementia, respectively (p<0.001 between groups). Caregiver informal care costs were the greatest contributor to total societal costs and amounted to €1370, €1223 and €2223 per patient per month for mild, moderate and moderately severe/severe AD dementia groups, respectively (p<0.001 between groups).; Conclusion: Total Italian societal costs generally increased with increasing AD dementia severity. However, costs were slightly lower for moderate than for mild AD dementia, possibly reflecting the observed unusual trend of greater caregiver time and higher memantine use in patients with mild versus moderate AD dementia.