We report on an example of odd even effect in self-assembled peptide amphiphiles (PAs) forming a cylindrical nanofiber. Minimum energy of the nanofiber depends on whether there are odd or even number of layers and whether each layer has odd or even number of PAs. More specifically, minimum energy for a nanofiber built of odd number of layers is achieved if each layer has even number of PAs uniformly, and radially aligned with alkyl chains in the center. On the other hand if the number of layers is even, energy is minimized if each layer has an odd number of PAs. (C) 2014 Elsevier B.V. All rights reserved.