Hypocalcemia is a rare cause of reversible heart failure. We reported a 40-year-old woman who had severe heart failure resistant to the usual antifailure therapy. She had severe hypocalcemia due to hypoparathyroidism after strumectomy. Echocardiography showed a large left ventricle with very low ejection fraction of 25% and moderate mitral regurgitation. After supplementation of calcium and vitamin D, her clinical situation and hemodynamics improved rapidly. At 15 months, myocardial impairment resolved fully. In conclusion, hypocalcemia should be considered in the differential diagnosis of resistant severe heart failure.