10 cases of aorto-pulmonary window were operated over a period of 22 yr. Surgery was performed under cardiopulmonary bypass (9 cases) or surface moderate hypothermia (1 case, 1955). Technique of correction was transaortic patching (5 cases), transpulmonary patching (2 cases), transpulmonary suture (1 case operated under moderate hypothermia), external section and suture (2 cases). 2 patients died in the immediate postoperative course. 8 long term survivors are still living 3 to 20 yr later, and leading a normal or nearly normal life. 7 were reevaluated (near follow-up time: 13 yr): 5 have an excellent result, 2 a good clinical result, contrasting with poor hemodynamic station (persistence of severe pulmonary hypertension, with 1 residual shunt). These data suggest that aorto-pulmonary window must be closed as early as possible, to prevent the development of a fixed high pulmonary resistance. The technique recommended is transaortic patching.