The efficacy and safety of the kampo medicine Yokukansan (YKS, TJ-54) in the treatment of behavioral and psychological symptoms of dementia (BPSD) were investigated in patients with Alzheimer's disease (AD) in an open-label study. This study included 26 patients who had been diagnosed as having AD and were not treated with donepezil hydrochloride. These patients were administered YKS (7.5g/day) for four weeks to investigate the changes in neuropsychological test results and care burden in the period from the start to completion of the study treatment. The Neuropsychiatric Inventory (NPI) was used for evaluation of BPSD, the Mini-Mental State Examination (MMSE) for evaluation of cognitive functions, the Zarit burden interview for evaluation of the caregiver's burden, Disability Assessment of Dementia (DAD) for evaluation of activities of daily living (ADL) and Self-Rating Depression Scale (SDS) for evaluation of the caregiver's depression. No significant change was seen in MMSE and DAD after four weeks of treatment, but the mean NPI total score decreased significantly. Furthermore, among the NPI subscales, a statistically significant decrease in score was not seen, however, a clinically significant decrease was seen in terms of hallucinations, agitation, anxiety, irritability or abnormal behavior. No significant changes were seen in caregiver's burden after four weeks of treatment. No serious adverse reactions to YKS were observed. The results of this study suggested that YKS may be an effective and well-tolerated drug in the treatment of BPSD in AD patients.