Small amphiphilic peptides are attractive building blocks to design biocompatible supramolecular structures via self-assembly, with applications in, for example, drug delivery, tissue engineering, and nanotemplating. We address the influence of systematical changes in the amino acid sequence of such peptides on the self-assembled macromolecular structures. For cationic-head surfactant-like eight-residue peptides, the apolar tail amino acids were chosen to systematically vary the propensity to form an a-helical secondary structure while conserving the overall hydrophobicity of the sequence. Characterization of the supramolecular structures indicates that for short peptides a beta-sheetsecondary Structure correlates with ribbonlike assemblies while random-coil and a-helical secondary Structures correlate With assembly of rods.