OBJECTIVES: To estimate the national costs of prescription medications for childhood attention deficit hyperactivity disorder (ADHD) in the United States (U.S.) in 2010 and to identify differences in diagnosis and costs by gender and racial/ethnic background.  METHODS: To determine childhood ADHD diagnosis and prescription medication use, we used ICD-9 and drug ID codes recorded from pediatric visits in the 2010 National Ambulatory Medical Care Survey (NAMCS). Our analysis included all formulations of the following medications: amphetamine salts, atomoxetine, dextroamphetamine, dexmethylphenidate, and methylphenidate. To calculate the costs of medication use, we multiplied the 2010 average wholesale price (AWP) by a presumed usual number of yearly doses and weighed these costs to reflect national estimates. We compared differences in overall medication cost by gender and race using the student's t test and evaluated differences in the proportion of patients diagnosed with ADHD using the chi-square test. RESULTS: Among pediatric visits in 2010, we found that 5.70% (n=7,201,548) were associated with a diagnosis of ADHD and, of those diagnosed, 67.29% (n= 4,846,163) had a mention of a prescribed ADHD medication. The nationally weighted sum of ADHD medication cost was $6.62 billion (mean=$1,336, SD=$1,220). Amphetamine salts prescriptions were associated with the highest overall cost ($3.67 billion). Overall drug expenditure did not differ by gender or race. We found a higher proportion of males were diagnosed with ADHD than females (7.97% vs. 3.48%, P < 0.001). Diagnosis with ADHD was less frequent among white children as compared with African-American children (5.79% vs. 7.09%, P = 0.012). CONCLUSIONS: We found that 5.70% of 2010 U.S. pediatric visits had a mention of ADHD diagnosis. We estimated that in 2010 U.S. expenditure for ADHD medications was $6.62 billion. Diagnosis of ADHD was more frequent among males and African-American children and less frequent among females and whites.