A comparison study was conducted to determine if a gender difference could be detected using an animal model for causalgia. The sciatic nerve was tightly ligated so that 1/3 to 1/2 of the nerve thickness was trapped by the ligature, just distal to the point at which the posterior biceps semitendinosus nerve branches off the common sciatic nerve. By measuring paw withdrawal from innocuous stimulation with Von Frey filaments, the percent of rats displaying average mechanical sensitivity of the injured paw that was significantly elevated compared to sham or unoperated control animals (days 22-24) was 28.6% for the male group versus 63.6% for the female group. Our animals did not display a consistent response in withdrawal latency to heat applied to the plantar surface of the root (hyperpathia). The data suggests that female rats are significantly more susceptible to developing neuropathic pain than male rats using this experimental model for causalgia.