Background: While behavioural or cognitive-behavioural therapy (BT/CBT) is recommended as the psychotherapeutic treatment of choice for children and adolescents with obsessive-compulsive disorder (OCD), the application of BT/CBT to paediatric OCD may not be straightforward. Objectives: This review examines the overall efficacy of BT/CBT for paediatric OCD, its relative efficacy against psychopharmacology and whether there are benefits in using BT/CBT combined with medication. Search strategy: We searched CCDANCTR-Studies and CCDANCTR-References (searched on 5/8/2005), MEDLINE, EMBASE, PsycINFO, the reference lists of all selected studies and handsearched journals specifically related to behavioural treatment of OCD. Selection criteria: Included studies were randomised controlled trials or quasi-randomised trials with participants who were 18 years of age or younger and had a diagnosis of OCD, established by clinical assessment or standardised diagnostic interview. Reviewed studies included the standard behavioural or cognitive-behavioural techniques, either alone or in combination, compared with wait-list or pill placebo. Data collection and analysis: The quality of selected studies was assessed by two independent reviewers. The primary outcomes comprised of endpoint scores on the gold standard clinical outcome measure of OCD symptoms, distress and interference (CY-BOCS) and endpoint OCD status. Main results: Four studies with 222 participants were considered eligible for inclusion and for data extraction. Two studies showed significantly better post-treatment functioning and reduced risk of continuing with OCD at post-treatment for the BT/CBT group compared to placebo or wait-list comparisons. We suggested that the POTS 2004 result, equal to a difference of about eight points on the CYBOCS, represented the best available estimate for the efficacy of BT/CBT relative to no treatment. (WMD -7.50; 95% CI -11.55, -3.45). Pooled evidence from two trials indicated that the efficacy of BT/CBT and medication did not differ significantly (WMD-3.87; 95% CI -8.15, 0.41). There was evidence of the benefit of combined BT/CBT and medication compared to medication alone (WMD -4.55; 95% CI -7.40, -1.70), but not relative to BT/CBT alone (WMD -2.80; 95% CI -7.55, 1.95). The rates of drop out suggested BT/CBT is an acceptable treatment to child and adolescent patients and their families. Authors' conclusions: Although only based on a small number of studies, behavioural or cognitive-behaviour therapy appears to be a promising treatment for OCD in children and adolescents. It can lead to better outcomes when combined with medication compared to medication alone. Additional trials are needed to confirm these findings. In the interim, consideration should be given to the ways in which BT/CBT might be made more widely available as a treatment for OCD in children and adolescents.