Intracardiac masses are rare in infants and children. Early detection is essential to their successful management. We present seven patients in whom echocardiography established the diagnosis and was crucial in the management. Three of the masses were primary cardiac tumors and four were thrombi. Patient 1: an infant with a calcified left ventricular fibroma. Patient 2: a neonate who presented with cyanosis due to obstruction of the right ventricular inflow tract by a fibroblastic tumor. Patient 3: an infant with a right atrial myxoma presenting as sepsis. Patient 4: a child who had a pulmonary embolus after a pulmonary valvotomy and was found to have a right ventricular thrombus. Patient 5: a child with a right atrial thrombus following a Fontan procedure for univentricular atrioventricular connection. Patient 6: a child with a left ventricular thrombus due to a dilated cardiomyopathy in association with epidermolysis bullosa. Patient 7: An infant with bilateral lobar emphysema, an aorticopulmonary window with left ventricular fibroelastosis, who developed a left ventricular thrombus.