OBJECTIVE: Sleep problems are common in children with attention-deficit/hyperactivity disorder (ADHD), yet little is known about sleep medication use in this population. The aim of this study was to describe sleep medication use, as well as associated child and family characteristics in school-aged children with ADHD. METHOD: Sleep medication use was ascertained using a prospective parent-completed seven-night sleep and medication log. Exposure variables included socio-demographic characteristics, total sleep problem severity (Children's Sleep Habits Questionnaire), ADHD severity and subtype (ADHD Rating Scale IV), ADHD medication use, internalising and externalising co-morbidities (Anxiety Disorders Interview Schedule for Children/Parent version IV) and parent mental health (Depression Anxiety Stress Scale). RESULTS: Two hundred and fifty-seven children with ADHD participated and of these 57 (22%) were taking sleep medication (melatonin 14% and clonidine 9%). Sleep medication use was associated with combined-type ADHD and ADHD medication use. The presence of co-occurring internalising and externalising co-morbidities was also associated with sleep medication use in ad hoc analyses. CONCLUSION: Sleep medication use is common in children with ADHD and is associated with combined-type ADHD and use of ADHD medication. Further research is needed on the broad functional benefits and long-term safety of sleep medication in this population.