Ethanol has become one of the main components for reformulated fuels because it is able to comply with environmental regulations. Biofuels have great advantages due to their physical and chemical characteristics, raw materials and production costs. However, they also have some disadvantages, mainly in terms of their compatibility with existing materials. Some components that are normally compatible with gasoline can be degraded by the presence of ethanol in fuel. The aim of this study was to evaluate the physical and chemical behavior of different polymeric materials typically used in autoparts, exposed in a mixture of gasoline and ethanol. To evaluate the resistance to degradation of the polymer samples, a continuous immersion test was performed according to SAE 1748. The effects of the 20% ethanol -80% gasoline mixture (E20) were examined by comparing changes in gain/loss of mass and by measuring the Shore-D hardness of the material at the end of exposure. The characterization of polymers was carried out before and after exposure by using the techniques of differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). In general, polymeric materials submerged in gasoline showed negligible changes in mass. Samples of POM, HDPE, PA6/6 and PA6 exposed to E20 showed mass increases below 10%. The chemical structure and mechanical properties (hardness) of the evaluated polymers were not significantly affected by the E20 blend with the exception of PA66. Since significant changes were observed in the thermal properties of this polymer, it can be concluded that it was at the limit of compatibility. (C) 2011 Elsevier Ltd. All rights reserved.