BACKGROUND: During the course of dementia, most people develop some type of neuropsychiatric symptoms (NPS), which result in lower quality of life, high caregiver burden, psychotropic drug use and a major risk of institutionalization. Studies on NPS in people with dementia have been mainly conducted in clinical centres or psychiatric services. OBJECTIVES: To investigate the course of NPS in people with dementia in primary care. METHODS: Analysis of (cumulative) prevalence and incidence, persistence and resolution based on data collected during an assessment at home of a prospective naturalistic cohort study in primary care in a sample of 117 people with dementia and their informal caregivers. Subsyndromes of NPS were assessed with the Neuropsychiatric Inventory (NPI) and Cohen-Mansfield Agitation Inventory. Multivariate analyses were used to detect determinants for the course of NPS. RESULTS: The mean age of the people with dementia was 78.6 years, and 52% were female. Mean Mini-Mental State Examination total score was 19.5, mean NPI total score 15.7. The most prevalent clinically relevant subsyndromes of the NPI were hyperactivity and mood/apathy, and the most prevalent individual NPS were aberrant motor behaviour (28%), agitation/aggression (24%) and apathy/indifference (22%). Of the people with dementia, 72.3% had one or more symptoms of the mood/apathy and 75.3% of the hyperactivity subsyndrome. CONCLUSIONS: GPs should be aware of NPS in people with dementia and should actively identify them when they visit these patients or when informal caregivers consult them. Timely diagnosing facilitates adequate professional care.