This guideline has been developed to advise on the identification, treatment and management of obsessive-compulsive disorder (OCD) and body dysmorphic disorder (BDD). Although distinct disorders, OCD and BDD share a number of common features and there is a high degree of similarity between the treatments for the two conditions. The guideline recommendations have been developed by a multidisciplinary team of healthcare professionals, people with OCD, a carer and guideline methodologists after careful consideration of the best available evidence. It is intended that the guideline will be useful to clinicians and service commissioners in providing and planning high quality care for those with OCD and BDD while also emphasising the importance of the experience of care for people with OCD, BDD, and carers. This guideline addresses aspects of service provision, psychological and pharmacological approaches for those with OCD and BDD from the age of 8 upwards. Although the evidence base is rapidly expanding, there are a number of major gaps and future revisions of this guideline will incorporate new scientific evidence as it develops. The guideline makes a number of research recommendations specifically to address these gaps in the evidence base. In the meantime, we hope that the guideline will assist clinicians, people with these disorders and their carers by identifying the merits of particular treatment approaches where the evidence from research and clinical experience exists.