Antidepressants differ in their effectiveness for treating attention-deficit/hyperactivity disorder (ADHD) in adults and children. None are as effective as psychostimulants for treating the attentional and cognitive symptoms, but they can help reduce impulsive and hyperactive behavior. Tricyclic antidepressants have well-demonstrated efficacy in treating behavioral symptoms, but desipramine should be avoided, at least in youths and adolescents (and perhaps adults), because safer tricyclics are available. Bupropion was effective in its few controlled trials, but tics and (especially in youth) skin rash limit its value. Venlafaxine appears effective, but controlled studies are needed. Serotonin selective reuptake inhibitors have not been tested in controlled trials, but they cause inconsistent changes, often aggravate ADHD symptoms, and can cause frontal apathy and disinhibition. Clonidine has not been adequately examined but seems to have small or uncertain effects. Psychostimulants remain the treatment of choice because of their unique effect on attention. Multimodal treatments (medications plus psychosocial) might not be more effective than medications alone.