A case of unusual longevity to the age of 58 years is reported for a female patient with complete transposition of the great arteries. The association with a wide atrial septal defect with intact interventricular septum may have contributed to the long survival without surgery. Factors determining intercirculatory mixing and systemic oxygen saturation may be the high pulmonary flow, the location of the anatomic communication, sufficient hemoglobin concentration to allow an adequate level of systemic resistance and recirculated systemic flow, and the belated development of pulmonary vascular disease.