Forty-three consecutive patients with previous balloon atrial septostomy have undergone a Senning type repair of transposition of the great arteries without patch augmentation of the atrial septum. A technique was used that allows expansion of the atrial septum without the use of additional foreign or autogenous materials. The operative (30-day) mortality rate was 4.6% (2/43) with no late deaths. A mean follow-up of 20 months shows that 83% of the patients are in sinus rhythm and none of these patients have clinically detectable caval or pulmonary venous obstruction or baffle leaks. In patients selected for atrial switch, the Senning operation may be performed without patch augmentation of the septum. Performed by the method described herein, the operation provides predictable early and late results with a low prevalence of arrhythmias. Significant venous obstruction has not occurred.