The authors examined the prevalence and correlates of anosognosia in a consecutive series of patients with probable Alzheimer's disease (AD). Patients were examined with the Anosognosia Questionnaire-Dementia (AQ-D), which showed good reliability and validity. On the basis of the AQ-D scores, patients were divided into those with anosognosia (n = 21) and those without anosognosia (n = 52). Patients with anosognosia showed a significantly longer duration of illness, more severe cognitive impairments and deficits in activities of daily living, and higher mania and pathological laughing scores than AD patients without anosognosia. These findings suggest that anosognosia in AD may be part of a specific neuropsychiatric syndrome.