This double-blind study evaluated the efficacy and safety of risperidone or olanzapine vs. promazine in the treatment of behavioral and psychological symptoms in dementia(BPSD). Patients were required to be 65 years or older, to have DSM-IV diagnoses of Alzheimer's disease (AD), vascular dementia (VD) or a combination of both. A brain computerized tomography (CT) was performed for all the patients; 60 demented patients,27 men (45 %) and 33 women (55 %) were selected for this study. The University of California Los Angeles neuropsychiatric inventory (NPI) was administered at baseline, then after 4 and 8 weeks. Patients had at least a score of 24 or more. The Hoehn and Yahr scale was used for evaluating parkinsonism. The scales were administered by an examinator who was not aware of the kind of treatment of the patients. After a wash-out period of 10 days,20 patients, 9 men and 11 women, mean age 76.6 +/- 6.0 years, were randomly assigned torisperidone 1 mg daily in divided doses (morning and bedtime) (Group A); 20 patients, 9 men and 11 women, mean age 82.5 +/- 9.3 years were randomly assigned to olanzapine 5mg at bedtime (Group B), and 20 patients, 9 men and 11 women, mean age 77.6 +/- 4.6 years, were randomly assigned to promazine 50 mg daily (morning and bedtime) (Group C). In case of lack of clinical response, after 4 weeks, the dose could be increased to 2 mg/day of risperidone, 10 mg/day of olanzapine, and to 100 mg/day of promazine in the respective groups. Repeated measures ANOVA was used for the statistical analysis of rating scales over time (baseline, 4 and 8 weeks). At the end of the 8th week, a global improvement was obtained in 80% of patients treated with risperidone and olanzapine, vs. 65 % of patients treated with promazine (p < 0.01). The results show that risperidone in doses of 1-2 mg/day and olanzapine in doses of 5-10 mg/day are effective and safe in the treatment of BPSD. Risperidone presents a major and dose-dependent antidopaminergic action and seems to be preferable when hallucinations and delusions are prevailing symptoms, even if it gives good results on aggression and wandering. Olanzapine seems to be faster in its sedative effect, probably for H1 receptor blockade. Moreover, 5-HT6 antagonism may favor acetylcholine release and this explains why these patients have not presented a cognitive worsening. However, both drugs are comparable or even superior to promazine, with significantly fewer side effects of both anticholinergic and extrapyramidal character.