In this paper I analyze the integration of the Dutch corporate governance code, Code Tabaksblat, within the companies that are listed on the Dutch AEX index. I looked at the total compliance of the firms with the Code, at the information provided by the firms on corporate governance and also at the relevance of corporate governance. To do so I have used the available information on the Code in their annual reports and on their websites for the years 2004, 2005 and 2006 and set up a total sheet to do the testing. To check whether or not the effect of corporate governance can be measured I used several studies from all over the world to get to a conclusion as accurate as possible. The results show that Code Tabaksblat is already quite integrated into the Dutch market as a high compliance percentage of around 90% can be observed. The supply of information is however not as good as a lot off differences can be observed in the way and extent of reporting. Finally, making a conclusion on if the effect of corporate governance can be measured is difficult as in most cases an effect is observed but this effect cannot be allocated to only one variable, corporate governance, as also other variables such as the development of a country come into play.