Barry McGaw, Education Director of the OECD until December 2005, has described and evaluated the current programme of international comparative assessment surveys, notably the PISA programme. Any international survey will have its stronger and its weaker points. With a high profile programme like PISA, there is a risk that the limitations will be overlooked by politicians eager to introduce reforms in a globalised information society. Five years have passed since the first publication of PISA results in December 2001. In Denmark, the results have led to profound educational reforms, but also to a number of supplementary studies that have examined and questioned the value of PISA and other international studies. (Contains 1 note.)