Most patients (90-95%)with major limb amputations experience a phantom limb--the vivid impression that the limb is still present. In many cases, the sensation is painful for reasons that are currently not well understood. A small subset of amputees (<10%) never experience phantom limb pain (PLP), the painful sensation felt in the amputated limb. This difference suggests that there may be a genetic component that precludes some patients from ever experiencing PLP. Understanding the genetic components of PLP may help in predicting which patients will experience PLP and which amputees will respond to the various treatment options available.