Electrospinning is reported for viscoelastic aqueous solutions of poly(ethylene oxide) (PEO) and with added nanoclay (laponite). A weak correlation between fiber diameter and the spinning solution's zero-shear viscosity is observed and compared with previous work reported by McKee et al. (McKee et al., Macromolecules 2004, 37, 1760). A new analysis of electrospinning results for PEO indicates a universal correlation between fiber diameter and solution properties that does not include shear viscosity as a primary variable. The addition of laponite nanoclay to the PEO solutions, which has been previously shown to result in rheologically simple solutions, leads to different fiber morphologies for the same shear viscosity in contradiction with reports for titania particles (Drew et al., J Macromol Sci Part A: Pure Appl Chem 2003, 40, 1415). The research identifies additional physicochemical properties that are important in determining electrospun fiber morphology. (c) 2006 Wiley Periodicals, Inc.