In this review, we consider issues relating to the pharmacological treatment of young children with attention deficit hyperactivity disorder (ADHD). ADHD in preschool-age children has a profound impact on psychosocial function and developmental trajectory. Clinical studies on pharmacotherapies for ADHD in young children have expanded rapidly in the past 2 decades, providing some evidence of efficacy for both psychostimulant and non-psychostimulant medications. However, preschool children may be more susceptible to adverse effects of medications, including growth reduction and cardiovascular side effects. Many questions remain regarding the long-term safety and effectiveness of these interventions; thus more research is needed to help clinicians evaluate the risk-benefit ratio for preschoolers with ADHD. As this body of knowledge grows, providers should consider the level of impairment caused by current symptoms in the risk-benefit analysis. Families should be educated not just about potential effects of medication but known complications of untreated ADHD; parents will likely not fully appreciate the long-term psychological effects of chronic behavioral problems and underachievement on a young child. A blanket "wait and see" approach should be avoided, in order to prevent a permanent loss of self-esteem and motivation that may affect some children throughout their lifespan.