A teratoma of the cardiac skeleton, a rhabdomyoma of the right ventricle and an intramural fibroma in the left ventricle were observed in three children, aged eight weeks, eight months and eight years, respectively. Atrial myxoma was found in a 42-year-old and a 49-year-old patient. History and symptoms showed no particular common features in the various patients, merely signs of flow obstruction in four of the five patients. Amongst specific cardiological diagnostic methods only angiocardiography was reliable in the demonstration of intra- or paracardiac space-occupying lesions. All five patients were successfully operated on under cardiopulmonary bypass. The surgical technique varied according to localisation, extent of the tumour and its site in relation to essential cardiac structures. Follow-up examination indicated that the patients were free of symptoms and recurrence.