The interaction with phospholipids of two lipid transfer proteins (LTPs) extracted from wheat and maize seedlings has been studied using the monolayer technique as a simplified model of biological membranes, Attenuated total reflectance IR spectroscopy has been used to monitor changes in the organization of dipalmitoylphatidylglycerol monolayers, induced by the incorporation of LTPs. In addition, the secondary structure of these proteins and the orientation of their helical segments with respect to the monolayers have been determined. The results show that maize LTP is more efficient to penetrate lipid monolayers than the wheat LTP, The insertion of the maize LTP within the lipid monolayers disrupt the organization of the lipid acyl chains while the wheat LTP does not alter the organization as markedly. When bound to lipid monolayers, these two proteins are predominantly ct-helical, with the similar orientational preference. These results demonstrate that, in spite of having a similar overall conformation, the two LTPs exhibit different surface binding properties that might be at the origin of the difference in their lipid transfer activity.