As the language presentation of children with attention deficit (hyperactivity) disorder (ADHD) is highly complex, this study aims to delineate the profile of a cohort of 40 children with ADHD, aged between 9 and 12 years, attending a child and adolescent mental health service (CAMHS). Speech and language therapists (SLTs) assessed the children on formal language tests (including tests of verbal comprehension/expression, vocabulary, reading and communication) over three one-hour sessions. Group demographics showed a predominance of males, with a greater number of children presenting with the "combined" subtype of ADHD over other subtypes (i.e. "predominantly inattentive" or "hyperactive-impulsive type"). The majority of the children also had a secondary psychiatric diagnosis. Test findings revealed some common trends in the overall group's performance, but a general ADHD-specific language profile was not discernible. Almost three-quarters of the study cohort had previously undetected language difficulties, with over 70% of those having "both" receptive and expressive language difficulties. Just under one-third of the cohort demonstrated reading difficulties. Relatively high correlations were found across performance on measures of verbal comprehension when compared to vocabulary and reading comprehension and expressive language. Most parents reported communication difficulties on completed questionnaires. The range, extent and complexity of the language difficulties of children with ADHD is demonstrated in our findings, with the heterogeneity of this population an obvious feature. Implications for further research and SLT clinical practice are discussed.