To examine in a community-based cohort: (1) the prevalence of chronic tic disorder (CTD) in children with attention-deficit/hyperactivity disorder (ADHD) compared with non-ADHD controls at ages 7 and 10; and (2) the additional psychiatric and functional burden of CTD in children with ADHD. Children aged 6-8 years with ADHD (n=179) and controls (n=212) were recruited through 43 Victorian schools using parent and teacher screening surveys (Conners 3 ADHD Index), followed by case confirmation (Diagnostic Interview Schedule for Children-IV (DISC-IV)). CTD was identified using the DISC-IV categories chronic motor tic disorder, chronic vocal tic disorder or Tourette syndrome at baseline and 36-month follow-up. Internalising and externalising disorders, social functioning, academic performance and quality of life were also measured. Tests of proportions and independent t-tests were used to compare the ADHD+CTD group with sex-matched ADHD alone children. Compared with controls, children with ADHD were 4.1 (95% CI 1.1 to 14.1) times more likely to have CTD at age 7, and 5.9 (95% CI 1.6 to 17.9) times more likely at age 10. Children with ADHD+CTD experienced higher rates of internalising disorders and peer problems, and poorer quality of life than those with ADHD alone. CTD prevalence is higher in children with ADHD compared with controls, and confers substantial additional psychiatric and functional burden. Clinicians need to consider CTD in both the initial assessment and ongoing management of children with ADHD, and address both the symptoms and the associated impairments.