Lithium carbonate is a widely used pharmacologic agent for acute bipolar disorder, long term prophylaxis of mania in a bipolar patient, and prevention of "manic overshoot" with an antidepressant in acute depression in a bipolar patient. Although clinical neurological associations with lithium overdose have been-established, there has been a dearth of reports of pathologic changes related to lithium toxicity. We report a case of a 52-year-old Black female with bipolar disorder who had been treated with lithium for over 5 years and who expired 24 days after presenting in a stuporous state with an elevated lithium level of 3.2 mEq/l. Postmortem neuropathologic examination revealed severe cerebellar atrophy of the internal granule and Purkinje cell layers with attendant Bergmann gliosis presumably resulting from chronic lithium use and toxicity. There was also Alzheimer type II cell change in the thalamus and lentiform nuclei possibly due to terminal uremia. In summary, this is a unique case which appears to illustrate cerebellar atrophic changes related to lithium therapy and acute lithium intoxication.