A successful preparation of polyamide 4 nanofibers via electrostatic spinning with diameters close to 100 nm is described. Polyamide 4 was prepared by the anionic ring-opening polymerization of 2-pyrrolidone and characterized. The effect of the system parameters (i.e., molar mass of the polymer, the solvent system) and the process parameters (i.e., the electrode-to-collector distance) during the electrostatic spinning have been studied. The morphology of the polyamide 4 fiber layers is given except molar mass of the polymer and the concentration of its solution primarily by the conformation of polyamide chains due to polyelectrolyte effect which was confirmed by viscosity measurements. (c) 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 2203-2210