Positive peer relationships are essential in healthy development. The prevalence of peer-relationship problems in children after acquired brain injury (ABI) has yet to be explored, although ABI does inevitably impact upon peer interactions. We aimed to explore how peer-relationships and emotional distress after ABI may differ from the levels reported by healthy children or mental health controls. Parents of 214 children (137 "healthy" children, 27 children using mental health services and 40 children with ABI) aged 9-15 years participated. A questionnaire measure of peer-relationship functioning and emotional distress was completed. Children with ABI experienced a greater degree of peer-relationship difficulties and emotional distress than healthy controls. No difference was found in reported peer relationship difficulties or emotional distress between ABI children and the children accessing mental health services. We conclude that emotional distress and co-occurring peer-relationship difficulties are as prevalent in a population of children after ABI as may be expected in a population of children under the care of mental health services, yet, unlike the latter group, appropriate intervention services are not commonly available. Interventions that aim to enhance peer relationships after childhood ABI may provide an essential resource to the benefit of outcome.