Organic coatings are widely used to protect metals against corrosion. In the absence of active anticorrosive pigments, the principal mechanism of corrosion protection consists in blocking of diffusion of corrosive agents like water or oxygen, (I). However, due to the heterogeneous character of paint films corrosion may occur. The anodic reaction is generally initiated at coating defects and drives the cathodic reaction in an adjacent region. From this follows that the knowledge of the composition and structure of corrosion films formed under the paint is of extreme importance in order to better understand the mechanisms of corrosion protection by organic coatings. During the last decade Raman spectroscopy has been successfully used for in-situ identification of corrosion products formed on various metals and different environments, (2-4). The main advantage of this technique is the possibility of in-situ structural and chemical identification of corrosion products formed on metals under potentiostatic control. There have been numerous studies that have tried to determine the nature of cor rosi on products formed on iron and galvanized steel after the deterioration of organic coatings (see for instance 5). However, most of these investigations are done in ex-situ conditions from which may follow changes in corrosion products when the sample is exposed to air or vacuum. Therefore, we report here for the f i r s t time in-situ Raman spectra of corrosion products formed after blistering of the paint which were obtained without removing the organic coating or the electrolyte. This work forms part of an investigation that aims to better understand the mechanisms of underfi I m corrosion.