The prevalence of depression in persons with dementia is controversial. Among 288 outpatients with dementia, a prevalence of 7.4% was found according to the Hamilton Rating Scale for Depression (HRSD), 8.0% using the Geriatric Depression Scale (GDS), and 6.3% according to DSM-IV criteria. Rates and levels of depression tended to be higher in vascular than in Alzheimer's dementia according to the rating scales, but not according to the DSM-IV criteria. Greater cognitive impairment was associated with higher HRSD (but not GDS) scores. Cases of clinical depression did not persist over 12 months' follow-up. These results sugguest that clinically significant depression in dementia is less common than previously reported and tends to remit.