Objective: The main aim of this study was to examine the age-dependent remission from ADHD in girls transitioning through childhood into adolescence and early adulthood. Method: We conducted a 5-year prospective follow-up study of 123 girls with ADHD and 106 non-ADHD control girls aged between 6 and 17 years at ascertainment. ADHD was considered persistent at follow-up if participants met full diagnostic criteria for "DSM-IV" ADHD or met residual criteria for "DSM-IV" ADHD with associated impairment (Global Age Forum [GAF] score less than 60). Results: By age 16 years, ADHD was persistent in 71% (95% CI = 61-79%) of girls with ADHD. Participants with persistent ADHD at follow-up had more psychiatric comorbidity, behavior problems, and functional impairment than girls with ADHD in remission. Remitted ADHD, however, continued to be associated with functional impairment relative to non-ADHD controls. Persistence at 5 years was predicted by increased behavioral impairment at baseline. Conclusion: This 5-year follow-up suggests that many girls with ADHD experience persistent symptoms and/or functional impairment through late adolescence and into early adulthood. (Contains 1 figure and 3 tables.)