The response surface methodology was used to model and optimize the electrospinning parameters for the spinning of regenerated nanoscale silk fibers from domestic silkworm, Bombyx mori. Electric field and silk concentrations were chosen as variables to control fiber diameter at different spinning distances. Fiber diameter was correlated to these variables by using a second order polynomial function. The predicted fiber diameters were in agreement with the experimental results. Response surfaces were constructed to identify the processing window suitable for producing nanoscale fibers. (C) 2004 Elsevier Ltd. All rights reserved.