In the present paper the interaction of four lipopeptides derived from the Pre S (120-145) sequence of the hepatitis B virus (HBV) with different lipids is described. The parent peptide structure was MQWNSTALHQALQDPRVGLYLPAGG. The peptide derivatives contained a residue of Pam3CSS, cholanoyl and stearoyl residues attached to their amino terminal end in order to modify the hydrophobicity of the peptide and to improve their potential antigenicity. The interactions have been studied using compression isotherms of monolayers and penetration kinetics. All the peptides showed surface activity and formed stable monolayers. The presence of these peptides under a monolayer of DPPC caused an expansion in the area occupied per molecule and modified the phase change of the DPPC.