The Behavioral Syndromes Scale for Dementia (BSSD) is a new instrument that showed strong internal consistency and interrater reliability in an outpatient sample of 106 patients with probable Alzheimer's disease. Factor analysis provided support for a priori symptom groupings, particularly the syndromes of disinhibition and apathy-indifference. Dependency (87%), denial of illness (63%), and motor agitation (55%) were common, while sexual disinhibition (2.9%) and self-destructive behaviors (2.9%) were rare. Virtually all symptoms were predominantly minimal to mild in severity. Patients with longer illness duration were more apathetic. Disinhibited behaviors and apathy-indifference increased with greater severity of dementia. Catastrophic reactions, aggression, and agitation were associated with greater functional impairment. There was great heterogeneity in symptom presentation. In Alzheimer's disease, several behavioral changes might be direct manifestations of underlying brain pathology, rather than being solely secondary to cognitive impairment.