The UK National Institute for Health and Care Excellence (NICE) is a non-departmental public body accountable to the Department of Health. NICE was established in 1999 in an attempt to reduce variability in the availability and quality of medical services in NHS to end the so-called `postcode lottery.` Since its establishment NICE has acquired an international reputation for the development of high quality, evidence-based clinical guidelines. NICE also makes cost-benefit assessments of certain technologies on the basis of effectiveness and cost effectiveness. In order to develop a NICE guideline related to psychiatry, the National Collaborating Centre for Mental Health establishes a Guideline Development Group that consists of technical experts, health and/or social care professionals, and lay representatives. The group searches for and evaluates the available evidence and formulates a series of clinical recommendations following which stakeholders are consulted and revisions occur. As well as providing treatment recommendations for healthcare professionals, the guidelines are also intended to inform patients, helping them make decisions and improving communication between patients and healthcare staff, and also to direct the focus of research. To date, NICE has published guidance on antenatal and postnatal mental health, antisocial personality disorder, attention deficit hyperactivity disorder, bipolar disorder, borderline personality disorder, dementia, depression, depression in children and young people, drug misuse (opioid detoxification and psychological interventions), eating disorders, obsessive-compulsive disorder, PTSD, schizophrenia, and the management of self-harm. We describe how, both directly through education and effects on clinical pathways, and indirectly through effects on health providers and patient behavior, NICE guidance has had an impact on psychiatrists working in UK.
 <Authors' abstract>