Background: Our objective was to describe the frequency of behavioural and psychological symptoms of dementia (BPSD) in community-dwelling elderly adults with cognitive impairment and to determine whether these symptoms and behaviours assemble into distinct, clinically relevant categories. Methods: BPSD were measured using the Dysfunctional Behaviour Rating Instrument (DBRI). Principal components analysis was used to detect effects in caregiver responses in the DBRI. Results: The DBRI was scored on 921 patients. The frequency of individual BPSD ranged from 20% (spouse not spouse) to 83% (repeating questions). The frequency of BPSD increased with decline in cognitive function. Behaviours sorted into five broad domains: Anger, Delusions/Paranoia, Withdrawn/Wandering, Agitation, and Repetitive Behaviours. Conclusions: BPSD are common in community-dwelling elderly persons with memory loss and may be aggregated into distinct, clinically relevant categories.