Interest in fabrication of nanofibers using electrospinning has recently increased due to the ability to produce fibers with controlled structures, orientations, and dimensions. Tensile properties of electrospun fibers have not been widely investigated due to the difficulties in handling nanofibers and measuring low load for deformation. In this study, the effects of process parameters on the mechanical properties of electrospun composite nanofibers of polycaprolactone and nanohydroxyapatite were experimentally investigated. Response surface methodology (RSM) was utilized to design the experiments at the settings of solution concentration, voltage, spinning distance and flow rate. Mechanical properties of the electrospun fibers were correlated with these variables using a third order polynomial function. It was found that polymer concentration, voltage and spinning distance were the most effective parameters. The predicted mechanical properties were in good agreement with the experimental results. (C) 2012 Elsevier Ltd. All rights reserved.