Idiopathic calcification of the coronary arteries is a rare hereditary condition of infancy. Complications include cardiac ischaemia, cardiac failure, and systemic hypertension. We present three patients with this condition, which in each case masqueraded as other cardiac diseases, with no indication of the specific diagnosis prior to autopsy.A 5 month old female presented with respiratory failure and hypertension and died within 24 hours of admission. All the coronary arteries were thick-walled, with narrow lumens. The aorta, great vessels, and renal arteries also showed thickening of the wall. Histology confirmed calcium in the internal elastic lamina of all vessels. The second patient was a female baby of 2 months, diagnosed with a large ventricular septal defect. She died suddenly prior to surgery. At autopsy, the orifice of the right coronary artery was reduced to a pinhole. The coronary arteries showed white patches of calcification, with associated ventricular infarction. The third patient was an 11 year old female who presented with cardiac failure, and had been diagnosed with dilated cardiomyopathy. Two weeks later, she died suddenly. The coronary arteries were patent, but firm with calcification and narrowed, with associated ventricular infarction. Our experience shows that idiopathic arterial calcification of infancy should always be considered in infants and children presenting with hypertension, cardiac failure, or sudden death.