Background: Production of methylphenidate (Ritalin), which is used to treat 90% of identified cases of ADHD, increased six-fold between 1990 and 1995. It is unclear whether this trend is associated with increased use of Ritalin to treat ADHD in children, adults, or both. Objective: To determine the prevalence of medication use for ADHD among grade school children in 2 school districts. Study Population: All students in grades 2-5 in Portsmouth (N=5,693) and Virginia Beach, VA (N=22,217) public schools. The 2 school districts are distinctly different in size and racial composition. Methods: School health databases developed for this study included all children enrolled in school, student age, grade, race, gender, medication, and the identification of every child to whom school nurses administered medication for ADHD. For Portsmouth, where census tract block group codes for student addresses were available, the SES characteristics of students' area of residence were examined in relation to risk of medication use for ADHD. Results: Prevalence rates of medication use for ADHD were consistent between the 2 school districts: 17% of Caucasian boys, 9% of African American boys, 7% of Caucasian girls and 3% of African American girls were given medication at school for ADHD. Ritalin was administered to 90.3% of children receiving medication for ADHD at school. Increased risk for use of ADHD medication in school was associated with residence in neighborhoods with increased median family income for Caucasian children (p<.001) and decreased public assistance for African American children (p=.006). Increased risk for use of ADHD medication in school was not associated with the percent of military personnel in a community. Conclusions: Prevalence rates of taking medication for ADHD among grade school children are substantially higher than previously reported, particularly for male, higher socioeconomic status, and Caucasian children. Diagnostic and school care issues have an important role in prevalence rates of ADHD medication among grade school children and thus warrant further investigation.