Abstract We presented a case of a 56-year-old man with giant pulmonary artery aneurysm caused by a misdiagnosed patent ductus arteriosus, severe multivalvular disease and active aortic valve endocarditis successfully treated by surgery. The correct diagnosis was missed despite preoperative diagnostics because the small patent ductus arteriosus was located at the distal part of common pulmonary trunk and a huge regurgitant signal overlapped its Doppler signal. Thorough evaluation of every patient, regardless of age, is necessary to recognize and treat this congenital anomaly.