Background. Anosognosia is common in patients with Alzheimer's disease (AD) and it is frequently related with an increase of time of care demand. Objective. The aim of the study was to examine the effect of anosognosia on the total costs of informal care in patients with AD. Methods. This was a prospective longitudinal study with community-dwelling AD patients. Anosognosia, the number of hours of informal care and the use of support services (p.e. home-care services, day care centers, etc.) were recorded at baseline and after 24 months. The cost of informal caregiving was calculated as 'market price'. Results. At baseline the prevalence of anosognosia was 54.3% (n=221), and 43.9% were classified as mild-AD. The average time spent on care was 5 hours/day ±2.4 (IADL: 1.3 h/d ±1.4 and BADL: 3.6 h/d ±1.5). Thirty percent of the patients used home care services, and 25.1% attended a day care center. Patients with anosognosia were more likely to use support services and received more time of care than did their asymptomatic peers. The presence of anosognosia increased the use of the support services after 24-months, including institutionalization. The mean cost of support services was 490.4 /month (SD=413.1 ; range=25-2,212.38 ), while the overall cost of care (support services plus informal care) was 1,787 /month (SD=972.4 ), ranging from 834.1 in mild-AD patients without anosognosia, to 2,424.8 in severe-AD patients with incident anosognosia. Conclusions. Anosognosia was associated with an increased number of hours of informal care, and a greater use of support services, regardless of the severity of the dementia, which lead to an increase of the total family-care costs.