Background: The histology of Cerebellar gray matter consists of a middle Purkinje cells layer with flask shaped Purkinje cells. The field of Neurology has documented that different organic compounds and metals are lethal to the excitatory Purkinje Neurons. Researches have proved Lithium to be hazardous to nervous tissue and especially Cerebellum For the past sixty years Lithium is the favorable drug for treatment of Bipolar Disorder.

Aim: To Analyse and record the changes of decrement of the size of Purkinje cell Diameter after chronic Lithium ingestion.

Methods: Sixteen albino rats were selected and were treated with lithium for a period of fifteen days and the data for changes in Purkinje cells Diameter was observed.

Results: The Observations of Our study showed highly significantly decreased diameter of the Purinje cells in Group B (Lithium Carbonate) animals as compared to Group A Animals which were on Lab Diet

Conclusion: The Morphometric Data proved that Lithium Carbonate is Toxic to Purkinje cells, and it educated our Population to use Lithium with caution.

Keywords: Purkinje cell Diameter, Gray matter, Hazardous