Amphilic basic polypeptides Poly(Leu‐Arg‐Arg‐Leu), 2Hcl, Poly(Tyr‐Lys‐Lys‐Tyr), 2Hcl and Ac(Leu‐Lys‐Lys‐Leu)4NHEt, 2TFA, formed by alternating doublets of hydrophobic and hydrophilic aminoacid undergo a coil to &agr; helix transition in the presence of lysolecithin and DMPC vesicles. Circular dichroism and31P NMR strongly suggest the formation of interactions between amino acid residues and phospholipid acyl chains.