According to the EU regulation EN NF 15376, bioethanol needs to be dehydrated prior to its use as a fuel. Hydrophilic membrane pervaporation is largely described as a promising alternative to molecular sieves and azeotropic distillation, the ordinary techniques for ethanol dehydration. Three major types of pervaporation membranes have been studied in the literature: organic (polymeric) membranes, inorganic membranes and hybrid membranes. Extensive research works have been focused on membrane overall performances (flux and selectivity). However, most of these studies did not systematically distinguish the contribution of the intrinsic parameters, i.e. membrane permeance or permeability (sorption-diffusion through the membrane) from that of driving force in the total flux determined. Moreover, in most cases, experiments were performed using ethanol that has undergone several distillations to remove volatile organic compounds impurities. Ethanol obtained from agricultural residues may contain high amount of volatile impurities. For example, the fermentation of grape marc produces bioethanol that contains methanol and some long chain alcohols. Such impurities can modify the performances of pervaporation membranes. This work aimed to study the performances of four pervaporation membranes: inorganic (Me-Si®), hybrid (Hyb-Si®) and two polymeric (PVA) membranes. These membranes were compared in terms of flux, permeance and selectivity using pure, binary (ethanol+water), ternary (ethanol+water+methanol) and complex (grape marc bioethanol) mixtures. Results show that, for a given membrane, permeance was not constant as often stated in the literature, but varied depending on operating conditions and mixture composition. Emphasis has been put on drag and competition effects involved between molecules. These key phenomena induced changes in membrane permeance and selectivity depending on feed mixture complexity. Keywords : Permeance, Membrane, Pervaporation, Dehydration, Bioethanol