N-[11-Trimethylammonioundecanoyl)-O,O'-didoecyl peptides, whose sequence is Phe-Phe-Glu, PhePhe-Phe-Glu, and Phe-Phe-Phe-Phe-Glu, formed an aggregate in CCl4. The-peptide part formed a parallel beta -sheet structure in the aggregate, which became tight with the increasing number of Phe residues. In contrast, the dodecyl chains became disordered when the strong interpeptide hydrogen bonding was formed. The orderly arrangement of the peptide part disturbed the orderly alignments at the dodecyl chains. Because of the discord between the H-bonding and the chain packing, the peptide-containing amphiphiles possessing more than three amide linkages will form not a crystallite but a lyotropic liquid crystal in CCl4.