Between 1975 and 1979, a group of 43 patients with d-transposition of the great arteries were diagnosed and underwent Rashkind balloon atrial septostomy at the time of initial catheterization. Thirty-six (88 percent) survived to the time of intraatrial baffle repair, and 31 (72 percent) are long-term survivors, 2 of them now awaiting repair. Palliative operations were performed in nine patients before definitive surgery; four of these patients are long-term survivors. Prostaglandin E1 infusion improved oxygenation and relieved acidosis in four patients. It is concluded that most patients with d-transposition of the great arteries will survive to elective intraatrial baffle repair between 6 and 12 months without surgical palliation in spite of significant hypoxemia. Prostaglandin E1 infusion may be lifesaving and provide sufficient palliation in patients with persistent hypoxemia and acidosis after balloon atrial septostomy.