Clinical guidelines are developed by professional societies and also, in England, by an independent non-departmental public body, the National Institute for Health and Care Excellence (NICE). Similarities and differences between these guidelines should be viewed in the context of different objectives, responsibilities and roles of guideline developers. This review describes the NICE clinical guidelines development principles and processes with the aim to provide the reader an informed perspective on the recommendations made. NICE clinical guidelines are developed by an appointed independent advisory committee comprising healthcare professionals as well as lay members, supported by a professional team comprising project managers, information specialists, systematic reviewers and health economists. Furthermore, registered stakeholders comprising organisations that have an interest in the guideline topic, or represent people whose practice or care may be directly affected by the guideline, are consulted on the draft scope and draft guidelines. NICE selects a limited number of high impact questions to be answered by the review of evidence, rather than cover a certain topic exhaustively as the clinical guidelines developed by professional societies may do. NICE clinical guidelines recommendations reflect both the clinical effectiveness and the cost-effectiveness of interventions.