Major depression is common among the elderly. Community-based researches indicate that around 4% of the elderly subjects are suffering from major depressive disorder. Because major depression is associated with prominent disability and increased incidence of suicide, depression has become a serious public health hazard. Primary for the elderly can be an important gatekeeper for major depression. Geriatric primary care physicians play an important role in the early detection and treatment of depression. Studies have shown that a systematic project to diagnose and to treat depression by primary care physicians can significantly reduce suicide rates. This article reviews important issues in the diagnosis and treatment of depressive disorders and offers a knowledge basis for geriatric physicians.