The purpose of present work was to characterize morphological alterations of rat hippocampal neurons after long-term (12-months) consumption of excessive doses of ionic fluoride (F – ). Material and methods. Male Wistar rats were assigned to four groups. Animals from control group were given drinking water with background F – content of 0.4 mg/L, rats from other groups received the same water with 5, 20 and 50 mg/L (as NaF). The morphology of neurons in CA 3 and CA 1 hippocampal areas was evaluated after staining of brain slices with toluidine blue according to Nissl’s method. Results . Long-term intoxication of rats with F – resulted in disorganization of cellular layer and decline in numerical density of pyramidal neurons in CA 3 and CA 1 hippocampal areas, which most probably indicates the death of a part of the cells. The neurons of both hippocampus zones exhibited such pathological changes as unequal distribution of Nissl substance, shifting of nuclei to periphery, cytoplasm vacuolization. Some neurons underwent swelling, other, in contrast, shrunk, spindle neurons or cells with spiral-like outgrowths were also visualized. In hippocampus of F – -exposed rats, the number of normochromic neurons decreased, but amount of hyperchromic and hypochromic cells increased. Conclusion . Long-term intake of excessive F – doses by the rats was established to induce dystrophic and necrobiotic changes of pyramidal neurons in CA 3 and CA 1 hippocampal zones. The revealed pathological processes can be a cause of disturbances in inter-neuronal communications in the hippocampus and lead to development of various neurological and cognitive disorders.