The natural history of congenital heart disease in older patients will become increasingly difficult to delineate, since many of uncomplicated defects were repaired early in life. Therefore the frequency of clinical and hemodynamic progress in non-operated patients with atrial septal defects seems to be of great interest. We are able to compare 27 patients aged more than 60 years with a group between 40 and 59 years. In 80 out of 103 patients totally, the clinical findings could be completed with catheterization data. The progress of deterioration with age in spite of intensive medical care could be demonstrated by mostly statistical significant signs of greater right-ventricular overload in the Ecg, cardiac arrhythmias--usually atrial fibrillation--changes in the X-ray findings and increasing pulmonary hypertension.