Twenty-one subjects with clinically diagnosed dementia of the Alzheimer type were rated on the Dementia Mood Assessment Scale, a new instrument intended to measure the severity of depressed mood in cognitively impaired patients. Ratings were based on direct observation and a semistructured interview of the patient. Interrater reliability was established. There were highly significant correlations between patients' scores on the instrument's 17-item depression subscale and their scores on global measures of depression and sadness. The potential usefulness of this new scale in assessing the severity of depression in demented patients longitudinally or under drug treatment conditions is discussed.