In a randomised, double-blind, 22-week trial 400 patients with dementia associated with neuropsychiatric features were treated with Ginkgo biloba extract EGb 761 (240 mg/day) or placebo. Patients with probable Alzheimer's disease, possible Alzheimer's disease with cerebrovascular disease or vascular dementia were eligible if they scored 9 to 23 on the SKT cognitive test battery and at least 5 on the Neuropsychiatric Inventory (NPI). EGb 761 was significantly superior to placebo with respect to the primary (SKT test battery) and all secondary outcome variables. The mean composite score (frequency x severity) and the mean caregiver distress score of the NPI dropped from 21.3 to 14.7 and 13.5 to 8.7, respectively, in the EGb 761-treated patients, but increased from 21.6 to 24.1 and 13.4 to 13.9, respectively, under placebo (p < 0.001). The largest drug-placebo differences in favour of EGb 761 were found for apathy/indifference, anxiety, irritability/lability, depression/dysphoria and sleep/nighttime behaviour.