A pathological study was conducted on an autopsied patient who had undergone amputation of the right arm at the level of the shoulder 38 years prior to death. The numbers of anterior horn cells, spinal ganglion cells and myelinated fibers in the anterior and posterior spinal roots at the cervical segments were examined quantitatively and compared with those of age-matched control subjects. On the amputation side, anterior horn cells, spinal ganglion cells and large myelinated fibers of the anterior and posterior roots were decreased in number. In addition, on the spared side, the medium-sized neurons of Rexed's lamina IX were shrunken, or decreased in number, and the number of small- and medium-sized myelinated fibers in the anterior roots was decreased. These findings indicate that the long-term effects of axonal amputation induce retrograde degeneration of the anterior horn and spinal ganglion cells on the amputation side, resulting in atrophy and a decrease of medium-sized neurons in the anterior horn even on the contralateral, spared side.