In 2002, SCIE established a basic guidance to govern the conduct of systematic reviews it commissioned. These were interim in recognition that much of the underlying methodology was still to be developed, and they were established as a general framework rather than a detailed set of procedures. . . . The current document updates the 2002 guidelines, reflecting the need to be more precise about SCIE’s expectations, to reflect the changing state of the art in systematic review methods and to outline a new structure for reports in order to respond more specifically to different audiences. As such, the document comprises a combination of guidance and general frameworks for review teams, to clarify SCIE’s expectations.