Several hydrophobic peptides were synthesized to construct supramolecular systems. Two types of supramolecular systems were constructed here by the peptides in different environments. First, spherical peptide aggregates in water were prepared by synthetic peptides composed of non-ionic amino acid residues. Conformation in aggregates was β-structure in the case of poly(Ala) segment and α-helix in the case of Aib-containing peptides. The structure of the peptide aggregates varied depending on constituents and composition possibly from core-shell type micelle, aggregate of reverse micelles, and vesicular structure. Second, self-assembled monolayer of hydrophobic helical peptides were prepared on gold surface with using complexation and hydrogen-bond formation between the peptides and functional groups fixed on gold. The orientation of helix axis in the peptide monolayer was closely vertical to the surface. These results indicate that hydrophobic helical peptides possess intrinsic self-assembling property.