Treatment with psychostimulant medication has been shown to improve scholastic functioning in children with attention-deficit/hyperactivity disorder (ADHD). However, the extent to which long-term academic gains are apparent in those having received such treatment remains elusive. This study examined prospectively the relationship of childhood stimulant treatment to academic functioning during adolescence. Children (n = 169) were initially recruited and diagnosed with ADHD when they were 7-11 years old. A subsample of those with childhood ADHD (n = 90) was reevaluated on average 9.13 (SD = 1.5) years later. Probands who did and did not receive treatment with stimulant medication were compared to each other and to a never-ADHD comparison group (n = 80) on three subtests from the Wechsler Individual Achievement Test-II (WIAT-II), as well as high school grade point average (GPA) and number of retentions in school as derived from school records. Analyses of covariance controlling for severity of childhood ADHD symptoms indicated that probands treated with psychostimulant medication achieved better academic outcomes, as measured by WIAT-II subtests and high school GPA, than those not treated with psychostimulants (p < .05). However, treated probands did not fare as well as the never-ADHD comparison group. Psychostimulant treatment for children with ADHD may benefit long-term adolescent academic performance, although the extent of improvement is likely to vary as a function of multiple factors.