Pathological examination was performed on a case of undifferentiated astrocytoma in a cow, which showed evident symptoms due to disturbances of central nervous system. The hen's egg-sized and well demarcated neoplastic tissue located in the convex part of the right parietal lobe in the cerebrum. Microscopically, the neoplastic cells were pleomorphic, fusiform or polygonal in shape and varied in size. Many cytoplasmic projections and proliferated glial fibers were noted.