Scottish Intercollegiate Guidelines Network: the first 15 years (1993-2008).

The Scottish Intercollegiate Guidelines Network (SIGN) was established in 1993. One of the first national programmes of evidence-based clinical practice guidelines, it has played a lead role internationally in many of the developments in guideline methodology. The challenges faced from the beginning of the organisation up to its integration into the National Health Service and how they were addressed are set out and related to SIGN's contribution to the Scottish tradition of medical education.