Described here is a case of accidental intrathecal administration of vincristine with pathologic findings in the central nervous system. A 3-year-old boy with acute lymphoblastic leukemia, was given his ninth course chemotherapy. Vincristine was accidentally injected intrathecally. The clinical course was rapidly progressive (6-day course) and resulted in death. An autopsy was done. The brain and spinal cord was grossly edematous and congested without any specific feature. Histologically, profound loss of neuron was noted in the spinal cord. Remaining neurons in the spinal cord, particularly anterior horn cells were markedly swollen. The spinal nerves show diffuse axonal degeneration and myelin loss. The upstream portion of the spinal cord (brain stem, cerebellum, cerebrum) showed patchy loss of neurons, especially Purkinje cells and granular cells of the cerebellar cortex. Many neurons showed axonal reaction (chromatolysis) with swelling. Several neurons show intracytoplasmic eosinophilic inclusion body. Myelin loss, axonal swelling and enlargement of perivascular spaces were seen throughout the white matter of central nervous system.