Over the last 10 years, clinical practice guidelines have increasingly become a familiar part of healthcare. Every day, clinical decisions at the bedside, rules of operation at hospitals and clinics, and health spending by governments and insurers are being influenced by guidelines. As defined by the USA Institute of Medicine, clinical practice guidelines are 'system­ atically developed statements to assist practitioner and patient decisions about appropriate healthcare for specific clinical circumstances'.1 They may offer concise instructions on which diagnostic or screening tests to order, how to provide medical or surgical services, how long to hospitalise patients, or other details of clinical practice. Mental healthcare is no exception: one of the earliest 'evidence-based' guidelines produced in the US was on depression2 and the England and Wales National Institute for Clinical Excellence's (NICE) portfolio of guidelines in mental health is now beginning to accumulate.