Objective: The purpose of this study was to evaluate the effect of altitude on rates of ADHD. As decreased dopamine (DA) activity has been reported with ADHD and hypoxia has shown to be associated with increased DA, we hypothesized that states at higher altitudes would have lower rates of ADHD. Method: State estimates from the 2007 National Survey of Children’s Health (NSCH) report and 2010 National Survey of Children with Special Health Care Needs (NS-CSHCN) report were used to extract the percentages of youth ages 4 to 17 diagnosed with ADHD. Results: Both the datasets independently revealed that the prevalence of ADHD decreases with increasing altitude (R ² = .38, p < .001; R ² = .31, p < .001), respectively. This study controlled for potential confounds (e.g., low birth weight, ethnicity, and household size). Conclusion: These findings suggest a need for further investigation into the extent by which altitude may serve as a protective factor for ADHD.