To study clinical and pathogenetic aspects of depression in Alzheimer's disease (AD), 65 patients with AD have been studied. The higher frequency of depressive symptoms has been revealed in different types of AD and all stages of the disease. Different syndrome variants of depression have been found: anxious (35,4%), apathic (29,2%), depression with delusions (16,9%), hypochondriac (10,8%) and melancholic (7,7%). The variety of clinico-phychopathological signs and mechanisms of depressive pathology formation in patients with AD suggests its heterogenic character.