Abstract This study aimed at investigating the use of psychosocial interventions and psychotropic co-medication among stimulant-treated children with attention-deficit hyperactivity disorder (ADHD) in relation to the presence of psychiatric co-morbidity. Stimulant users younger than 16 years were identified in 115 pharmacies and a questionnaire was sent to their stimulant prescribing physician. Of 773 questionnaires sent out, 556 were returned and were suitable for analysis (72%). The results are based on 510 questionnaires concerning stimulant-treated children for whom a diagnosis of ADHD was reported. Of the 510 children diagnosed with ADHD, 31% had also received one or more other psychiatric diagnoses, mainly pervasive developmental disorder or oppositional defiant disorder/conduct disorder. We found an association between the presence of co-morbidity and the use of psychosocial interventions for the child (P < 0.001) and the parents (P < 0.001). In the ADHD-only group, 26% did not receive any form of additional interventions, while psychosocial interventions varied from 8 to 18% in children with ADHD and psychiatric co-morbidity. The presence of diagnostic co-morbidity was also associated with the use of psychotropic co-medication (overall, P = 0.012) and antipsychotics (P < 0.001). Stimulant-treated youths with ADHD and psychiatric co-morbidity received more psychosocial interventions and psychotropic co-medication than children with ADHD-only. The type of psychosocial interventions and psychotropic co-medication received by the children and their parents, depended on the specific co-morbid psychiatric disorder being present. ; phone: +31-71-5766157 (Faber, Adrianne) ; adrianne.faber@chello.nl (Faber, Adrianne) ; SIR Institute for Pharmacy Practice and Policy - Theda Mansholtstraat 5b - 2331 JE - Leiden - NETHERLANDS (Faber, Adrianne) ; University Centre for Child and Adolescent Psychiatry - Groningen - NETHERLANDS (Kalverdijk, Luuk J.) ; Department of Social Pharmacy, Pharmacoepidemiology and ...