Less is understood about the relationship between ADHD symptoms and academic performance in adolescents than the relationship in younger children. As such, the aim of the present study was to investigate the prospective relationship between ADHD symptoms and academic performance in a community adolescent sample. Three hundred and twenty-four participants, aged 15 and 16, in their final year of compulsory education, completed measures of ADHD, anxiety, depression, and motivation, and a test of general cognitive ability. Participants were also asked for permission for their academic grades to be viewed on a later occasion (approximately 6 months later). In regression analyses, ADHD symptoms were the most significant independent psychopathological predictor of academic performance, and were almost as significant as motivation and cognitive ability. The results suggest that adolescents with more ADHD symptoms are likely to encounter greater academic difficulties. (Contains 2 tables.)