Placebos have been shown to produce significant positive changes in several health and mental health problems, referred to as placebo effects. Although it is well established that stimulant medication is an empirically supported treatment for children with attention-deficit hyperactivity disorder (ADHD), little is known about the role of placebos in the medication treatment of children with ADHD. This article reviews existing studies that evaluate whether placebos produce significant changes in children with ADHD. Published literature and the author's own empirical work were used to evaluate whether placebo effects are present in the medication treatment of children with ADHD. There is little evidence that placebos produce significant changes in the behavior or cognition of elementary school-age children with ADHD. However, there may be significant placebo effects in adults who evaluate children with ADHD. Evidence suggests that parents and teachers tend to evaluate children with ADHD more positively when they believe the child has been administered stimulant medication and they tend to attribute positive changes to medication even when medication has not actually been administered. Several viable mechanisms for these placebo effects are suggested.