Objective: Baseline neurocognitive testing is used in amateur sports as a component of a comprehensive concussion management program. Baseline testing might be more important for athletes who have a developmental condition, such as attention-deficit hyperactivity disorder (ADHD). The purpose of this study was to determine whether adolescent girls with ADHD perform more poorly on ImPACT® than girls who do not have ADHD. Participants and Methods: The initial sample consisted of 2,618 girls between the ages of 13 and 18, who (a) spoke English as their primary language, (b) denied a history of neurological problems (i.e., epilepsy, meningitis, and brain tumors), and (c) obtained valid ImPACT® test scores during preseason testing in 2010. Of this sample, 100 (3.8%) girls self-reported a diagnosis of ADHD. A sample of 100 control subjects was precisely matched on age, sport, and number of self-reported past concussions. Results: The two groups were compared on the four primary composite scores using mulivariate analysis of variance (MANOVA) followed by univariate ANOVAs. There was a significant multivariate effect [Wilks’ Lambda=.91; F(4, 195)=5.1, p<.001, partial eta squared=.095]. The univariate ANOVA results revealed significantly worse neuropsychological test scores for girls with ADHD on the Visual Memory (p<.031; Cohen’s d=.31) and Processing Speed (p<.001, d=.57) composites. The groups did not differ on the Verbal Memory or Reaction Time composites. Mann Whitney U tests were used for the Impulse Control composite and the Post-Concussion scale due to non-normal distributions and heterogeneity of the variances. The girls with ADHD had worse scores on the Impulse Control composite (p<.033, d=.44) and they endorsed more symptoms (p<.001, d=.44) than the girls who did not have ADHD. Conclusions: Girls with ADHD performed more poorly on computerized cognitive testing with ImPACT®, and they reported more subjective symptoms, than girls who do not have ADHD.