BACKGROUND: The neuropsychiatric derangements in dementing patients are common and troublesome in their managements. The purpose of this study is to compare the behavioral changes in patients with subcortical vascular dementia (SVaD) and to those in patients with Alzheimer's disease (AD) by using the Korean version of the neuropsychiatric inventory (K-NPI). METHODS: The K-NPI was administrated to the close caregivers of 19 patients with AD (who met the criteria of the NINCDS-ADRDA for probable AD) and 14 patients with SvaD (who met the criteria of the NINDS-AIREN criteria for probable or possible VaD). Groups were matched for age, education and dementia severity. We evaluated the prevalence, the composite score (frequency X severity) of each behavioral domain in K-NPI between two groups. RESULTS: The most common behavioral disturbances were anxiety (63%) in AD and apathy/indifference (93%) in SVaD. Patients with SVaD had significantly greater total K-NPI scores than patients with AD and exhibited apathy/indifference, agitation/aggression and anxiety more frequently. Composite score of apathy/indifference over 4.7 point discriminates between AD and SVaD with accuracy of 75.8%. CONCLUSIONS: The K-NPI provides behavioral profiles that differentiate patients with SVaD from patients with AD. Patients with SVaD are more behaviorally disturbed. Clinicians need to pay more attention to the behavioral disturbances when managing the patients with SVaD.