Abstract Mammalian exposure to triethyltin (TET) leads to severe impairment of motor function. Spinal cord, rootlets of spinal nerve, sciatic nerve, and soleus muscle of TET-treated rats were examined to assess their involvement. Adult rats were exposed to TET bromide in drinking water (30 mg/liter) for 3 weeks. The spinal cord became edematous with vacuolar formation in the myelin of white and gray matter. Chromatolysis occurred in motor neurons of the ventral root. Myelin of ventral and dorsal rootlets of spinal nerve was also affected with ventral rootlets showing greater involvement. Minimal effect was seen in myelin of sciatic nerve. Soleus muscle contained atrophic myofibers and, after 3 weeks recovery, type-grouping of fast-twitch myofibers. Chromatolysis and type-grouping were regarded as indications of a degenerative effect of TET-treatment on peripheral axons. We conclude that the neuromuscular toxicity of TET has a myopathic and neuropathic component and that the involvement of the neuronal cell body and the denervation of myofibers may contribute to the peripheral motor dysfunction.