Before implementing a guideline, reassurance is needed that the guideline i
s valid, reproducible and reliable. A method for assessing guideline validi
ty has now been developed for general use. Guideline producers need to cons
ider suitable strategies for implementing their guidelines. When designing
and evaluating a guideline implementation strategy, three key questions nee
d to be addressed: what are the most suitable intervention techniques; what
are the desired effects of the guideline; and what will be the relevance o
f changes achieved? The time scale for the evaluation should also be determ
ined carefully.