Abstract Objective: To evaluate the outcome of the arterial switch operation (ASO) used to treat various anatomico-pathologic entities of transposition of great arteries. Patients and Methods: Fifty patients who underwent the arterial switch operation (ASO), done by one surgeon (Rene Pretre), at the university hos-pital Zurich -Switzerland during the period between July 1998 and No-vember 2003 , were retrospectively studied. Of the fifty patients included, there were 31 boys and 19 girls with a median age of 7 days and weight of 3.3 kg. The lesions treated included 41 d-transposition of great arteries (d-TGA), 8 double outlet right ventricle with subpulmonary ventricular sep-tat defect (DORW P- 8D) and one congenitally corrected transposition of great arteries (CC-TGA) with heart failure. Forty five patients underwent primary ASO. Four patients with concomitant hypoptastic aortic arch and isthmus stenosis underwent a two-stage repair. The patient with CC-TGA underwent PA banding followed by a double switch operation.