Lithium-associated hyperparathyroidism is one of the most common causes of hypercalcemia in patients taking lithium. We present an elderly patient who developed hypercalcemia secondary to chronic lithium therapy-induced hyperparathyroidism. He presented with tremors and myoclonus. It was precipitated by a concomitant intake of diuretics, leading to dehydration. Extracorporeal therapy for lithium removal was not given even though he had neurological symptoms, and he was managed with intravenous fluids. He promptly recovered and lithium was stopped. Lithium-related endocrinological manifestations should be investigated for, in any suspected case of lithium toxicity.