Objective: Study the prevalence and correlates of ADHD symptoms in the National Health Interview Survey (NHIS). Methods: NHIS includes 10,367 children ages 4 to 17. Parents report lifetime diagnosis of ADHD and complete the Strengths and Difficulties Questionnaire (SDQ). Prevalences of clinically significant ADHD and comorbid symptoms by race and ethnicity, gender, and age are presented. Results: Prevalence of clinically significant SDQ ADHD symptoms is 4.19% (males) and 1.77% (females). Male prevalence by race is 3.06% for Hispanics, 4.33% for Whites, and 5.65% for Blacks. Significant differences in prevalence occur across gender (p less than 0.01) and among males across race (p less than 0.01), age (p less than 0.01), and income (p less than 0.02). In the full sample, 6.80% of males and 2.50% of females have a parent-reported lifetime ADHD diagnosis but are negative for SDQ ADHD. Likewise, 1.59% of males and 0.81% of females are positive for SDQ ADHD but negative for parent report of ADHD diagnosis. SDQ ADHD positive children have substantially higher proportions of elevated scores on other SDQ subscales. Conclusion: ADHD symptoms vary by race and ethnicity, gender, and age and are associated with other emotional and behavioral difficulties. Both overdiagnosis and underdiagnosis of ADHD may be issues in the U.S. population of 4- to 17-year-olds. (Contains 5 tables.)