This case report describes two cases of dilated cardiomyopathy due to hypocalcaemia as a result of hypoparathyroidism. Patient A suffered from dilated cardiomyopathy due to secondary hypoparathyroidism as a result of previous neck surgery. Patient B suffered from dilated cardiomyopathy with congestive heart failure due to primary hypoparathyroidism. Hypoparathyroidism can exist for years before being recognised, especially after neck surgery. Besides standard treatment of heart failure, restoration of serum calcium levels with calcium and vitamin D supplementation can lead to rapid improvement of cardiac function and should be continued lifelong. Both patients were responding very well to heart failure therapy and calcium supplementation as ejection fraction improved after restoration of plasma calcium levels. This case report emphasises that hypocalcaemia should be in the differential diagnosis of heart failure.