Stimulants have been available for the treatment of attention-deficit/hyperactivity disorder (ADHD) for more than 70 years and are the most effective medications available. During the past 2 decades, several new immediate-release (IR) and extended-release methylphenidate (MPH) and amphetamine (AMPH) formulations have become available. These products differ by dose form (capsules, tablets, oral suspensions, oral disintegrating tablets, and patch), by onset and duration of effect, and by bioavailability. The side effect profile is generally similar for all compounds. Although the products are similar, individual patients may have a better response or tolerability to a particular class (MPH or AMPH) or formulation.