The available evidence suggests that amphetamine, methylphenidate, atomoxetine, cognitive behavioural therapy, and meta-cognitive therapy are associated with greater attention-deficit/hyperactivity disorder symptom reduction compared with placebo or supportive therapy. The evidence also suggests that the use of methylphenidate is associated with better functioning and cognitive skills than placebo. Large, well-designed trials that specifically address the treatment of attention-deficit/hyperactivity disorder in adults are needed to accurately assess the impacts on quality of life and attention-deficit/hyperactivity disorder-associated morbidities.