Abstract: The present study was designed to evaluate the neuropathological effect of Tributyltin (TBT) on the neurons of the cerebral ganglia in the land snail E. vermiculata. Sublethal dose (1/5 LD50) was used and the experiments lasted for 4 weeks. Light-and electron microscopical examination of treated animals revealed severe histopathological and ultrastructural alterations in the cerebral ganglia. These alterations included hyperchromatic, pyknotic or highly shrunken nuclei, extreme indentation of plasma membrane, atrophy of the perikarya of some neurons, margination of nucleoli, fragmentation or dilation of rough endoplasmic reticulum, damage of mitochondria and vacuolation and destruction of cytoplasm. In addition, degenerated synaptic vesicles and increased number of autophagosomes and myelin figures were frequently observed.