Depression, which affects approximately 6 million men in the United States, is associated with a high risk of mortality from comorbid medical illnesses and from suicide. Evidence suggests that depresssion affects men differently than women, and that older men in particular may experience special influences, symptoms, and consequences. The causes of late life depression can be divided into psychological, social, and biological factors. Special considerations for this population include laboratory studies to identify possible secondary medical abnormalities that may either accompany or derive from the depressed mood, and pharmacologic treatments that have been shown to be more efficacious in aging men. Research involving depressed hypogonadal and eugonadal men suggests that depressed men may benefit from testosterone augmentation.