The aim of this study was to assess the efficacy and safety of tandospirone, a 5-HT_1A partial agonist, for treatment of behavioural and psychological symptoms of dementia (BPSD). Thirteen outpatients with DSM-IV diagnosis of Alzheimer's type or vascular dementia were enrolled in this study. Their BPSD and cognitive functions were evaluated with the Neuropsychiatric Inventory (NPI) and Mini-Mental State Examination, respectively, for an 8-wk period of treatment. The maximum benefit of tandospirone was achieved at a mean dose of 19.6 mg/d. There were significant improvements in the NPI subscores for delusion, agitation, depression, anxiety, and irritability at 2 or 4 wk after the start of administration of tandospirone. No patients experienced severe adverse effects. The results suggest that tandospirone was effective at improving BPSD symptoms and well-tolerated in elderly demented patients.