PURPOSE: To determine the histopathological changes occurring after the injection of NBCA(n-butyl cyanoacrylate) into the subarachnoid space of the cat. MATERIALS AND METHODS: A 1: 4 NBCA-Lipiodol mixture was injected into the subarachnoid space of ten cats by cervical spinal tap. Two weeks later all cats were sacrificed, and histopathological examination of the cerebrospinal leptomeninges, blood vessels and parenchyma was undertaken. RESULTS: 1. Changes in leptomeninges: Foreign body giant cells were noted in five cases, fibrosis in six and acute inflammation in all ten. Chronic inflammatory change accompanied 7 of 10 acute inflammations. 2. Changes in blood vessels: One case was excluded because blood vessels were not included in pathologic tissue. Acute vasculitis was noted in six cases, thrombosis in one, and one showed fibrotic change without necrosis in the media of the vessel wall. Among the six with acute vasculitis, severe change was noted in one and mild change in five. 3. Changes in parenchyma: Mild parenchymal inflammation was discovered in two cases and mild infarction in one. Parenchymal changes were limited to the outer cortex. CONCLUSION: The injection of NBCA into the subarachnoid space of the cat caused toxic histopathological changes in the cerebrospinal meninges, blood vessels, and parenchyma.