Polyurethane (PU) nanofibers were prepared by the electrospinning method. The process parameters, including the applied voltage, feeding rate, and solution concentration, were investigated carefully. The results showed that the resultant nanofibers, electrospun from PU/N,N-dimethylformamide (DMF) solutions, had ultratine diameters ranging from about 700 to 50 nm. In addition, it was found that the diameters and morphology of the nanofibers were influenced greatly by the process parameters. In particular, the solution concentration played a main role in influencing the transformation of the polymer solution into ultrafine fibers, and the diameters increased with the solution concentrations increasing. Finally, it was concluded that uniform PU nanofibers without beads or curls could be prepared by electrospinning through good control of the process parameters, such as 5.0-7.0 wt % PU/DMF solutions, 10-15-kV applied voltages, and 0.06-0.08 mm/min feeding rates. (c) 2008 Wiley Periodicals, Inc.