Calcium plays a vital key role in cardiac automatism and excitation-contraction coupling, with low serum levels associated with myocardial contractility compromise especially if myocardial sarcoplasmic reticulum is unable to maintain enough calcium content to initiate normal cardiac contraction. We present a 42-year-old woman with postsurgical untreated hypoparathyroidism and severe hypocalcaemia manifested as acute heart failure, without underlying known cardiac disease. Hypocalcaemia is a rare and potentially reversible cause of cardiomyopathy, with very few cases reported in the literature. Restoration to normal serum calcium levels usually leads to a rapid improvement of cardiac function. This rare case report highlights the importance of considering hypocalcaemia as a potentially reversible cause of severe cardiac dysfunction. Exclusion of hypocalcemia due to surgical hypoparathyroidism is mandatory in any individual with acute heart failure previously subjected to thyroidectomy.