BACKGROUND It has been suggested that obstructive sleep apnea (OSA) may result in symptoms similar to those experienced in attention-deficit/hyperactivity disorder (ADHD). Because this may have important public health implications, we reviewed the literature regarding this association, with a focus on interventional studies examining the effect of OSA treatment on change in ADHD symptoms. METHODS We performed a systematic literature search of PubMed, along with other major databases, for interventional studies published between January 1966 and June 2010 that examined the effect of OSA treatment on ADHD, which resulted in 6 studies. The literature on the prevalence of ADHD symptoms in OSA and vice versa was also reviewed. RESULTS Attentional deficits have been reported in up to 95% of OSA patients. In full syndromal ADHD, a high incidence (20% to 30%) of OSA has been shown. All 6 interventional studies reported improvements in behavior, inattention, and overall ADHD after treatment of OSA. CONCLUSIONS OSA may contribute to ADHD symptomatology in a subset of patients diagnosed with ADHD (DSM-IV criteria). Treatment of OSA appears to have favorable effects on ADHD symptoms. Controlled trials and epidemiologic investigations will be required to better understand these relationships, as well as their diagnostic and prognostic implications.