The European Union's decision of adopting the International Accounting Standards for the whole of its countries members was deeply contested by the European banks. In fact, the banking industry was completely opposed to IFRS 39 which treats the financial instruments. This standard introduced the "Fair Value" as the principal evaluation model for financial instruments. This model will have very big impacts for the banks especially because of returns and equities inducted volatility. We tried to explicit the major anticipated repercussions of this evaluation model which have favored the opposition of European banks to many points of the actual project of IAS 39. To do it, we tried to study the case of the largest French banks which are (or which have subsidiaries) quoted in Paris Stock Exchange by using semi-directive deep interviews with persons in charge of the application of international accounting standards in these banking groups. We concluded that this refusal was motivated by the fact that many points of this accounting standard were judged as non adapted to banking activity. In addition, the use of models for the determination of fair value, in the case when it isn't given by market, will make banks accounts incomparable after they have succeeded to be so, behind many efforts.