Clinical guidelines are intended to provide healthcare staff with information, based on a systematic appraisal of the current best evidence, of the optimum methods of addressing specific aspects of patient care. These are beneficial in providing practitioners with accessible summaries of evidence and its application to clinical practice. However, clinical guidelines require evaluation before implementation to ensure that they represent the current best evidence of clinical efficacy and cost-effectiveness, and are applied in appropriate situations. They also present practitioners with a potential tension between standardisation of service, client choice and the use of clinical expertise in decision making. Nurses need to be aware of the issues that should be considered in appraising and implementing clinical guidelines. This includes evaluation of relevance to specific practice situations, quality and how they can be combined with an appreciation of individual client contexts and used in conjunction with clinical expertise to achieve high quality care.