Rigid-rod ß-barrels are composed of interdigitating, short, amphiphilic peptide strands flanked by stabilizing rigid-rod staves. We here report studies on the topological diversity of these recently devised artificial -barrels with regard to their length. For this purpose, homologous p-octiphenyl, p-sexiphenyl, and p-quarterphenyl rods were equipped with complementary tripeptide strands based on the sequences Lys-Leu-Lys and Glu-Leu-Glu. The stability of rigid-rod -barrels of different length was determined by denaturation with guanidinium chloride. Free energies of δGH2O = -5.2 kcalmol-1, δGH2O = -2.9 kcalmol-1, and δGH2O < -0.3 kcalmol-1 found for homologous p-octiphenyl, p-sexiphenyl, and p-quarterphenyl -barrels demonstrated strong dependence of -barrel stability on ß-barrel length. These results revealed a very qualitative minimal (~23 Å) and an ideal -barrel length (~34 Å), synergistic formation (α = 1.4) and remarkable stability for ideal p-octiphenyl -barrels exceeding that of several proteins and most synthetic models. Rigid-rod ß-barrels with p-oligophenyl staves longer than 34 Å will be very difficult to make and study because of rapidly decreasing rod solubilities. However, a strategy to bypass this apparent upper limitation of -barrel length is introduced: supramolecular matching of mismatched rods yielded elongated -ß-barrels (61 Å) of acceptable stability (δGH2O = 2.2 - 3.1 kcalmol-1).