A synthetic peptide, corresponding to the 110-121 sequence of VP3-HAV (hepatitis A virus) protein, was synthesized, and its interactions with membrane models were analyzed with monomolecular layer models. Surface activity measurements indicate that the peptide is able to modify the surface activity of water forming monomolecular films. Compression isotherms and penetration kinetics determinations suggest that the hydrophobic moiety of the peptide is able to insert into phospholipidic monolayers promoting an expansion. Moreover, as interactions are stronger with stearylamine-containing monolayers, an electrostatic effect cannot be discarded.