Attention-deficit/hyperactivity disorder (ADHD) is a common mental health condition that affects children, adolescents, and adults. Because it is a chronic condition and typically requires effective treatment for several years or more, information on the benefits and risks of long-term pharmacotherapy for ADHD is vital to clinicians. This article reviews the emerging literature on the safety of long-term stimulant medications in ADHD-the most commonly prescribed medications for this condition. Common side effects, including cardiovascular effects, growth effects, and tics, are discussed, as well as treatment of children younger than age 6 and evidence of carcinogenic and reproductive effects.