Behavioural and psychological symptoms of dementia (BPSD) are a frequent problem in patients with dementia. The consequences of these neuropsychiatric problems can be significant for both patient and caregiver. Although there is no universally accepted pharmaceutical intervention for the treatment of BPSD, various agents have been studied, including divalproex sodium (valproate semisodium). The results of four placebo-controlled clinical trials are reviewed. None of the studies was sufficient to define clinical practice and the results can be seen as conflicting and inconclusive. Three studies suggested possible short-term efficacy, tolerability and safety of divalproex sodium for agitation and some other neuropsychiatric symptoms associated with dementia in elderly patients; in two of these studies, the findings were obtained only on analysis of secondary outcomes. Benefits of divalproex sodium over placebo were not demonstrated in a fourth study. Further research is needed to determine the optimal use of divalproex sodium for the treatment of neuropsychiatric symptoms of dementia and the long-term benefits, if any, of its use in this patient population.