Electrospinning of low concentration polymer solutions has the advantage of producing fibers with small diameters, but unfortunately beaded fibers are often observed. This article reports the use of hyperbranched poly(ester amine) (PEA) as an additive for low concentration polymer solutions to eliminate beads and improve the fiber uniformity. Electrospinning of low concentration poly(methyl methacrylate) solutions was investigated. With only 1 wt %. hyperbranched PEA, the fiber Uniformity was significantly improved. The principle of improvement was investigated by measuring the solution properties, and it is inferred that the improvement is attributed to the significant increase in solution conductivity. The solution viscosity and surface tension only change slightly. The versatility of this approach was demonstrated by electrospinning low concentration solutions of two other polymers: polystyrene and polyoxymethylene. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115:3687-3696, 2010