Calcium is an essential electrolyte in impulse generation and contraction of cardiac muscle. Hypocalcemia can occur in cases of parathyroid hormone deficiency, primarily due to inadvertent removal of the parathyroid gland during thyroidectomy, however most cases are idiopathic. We present a case of an adult male who developed sustained narrow complex tachycardia due to hypocalcemia in the setting of untreated idiopathic hypoparathyroidism.