Twenty patients with atrio-ventricular canal malformations (5 complete and 15 partial forms) were operated upon during the last two years, using new surgical techniques. The repair of the complete form based on a three-leaflet three-commissure mitral valve concept, was accomplished by: a) Two separate partitioning patches (one ventricular, one atrial), b) mitral and tricuspid valve attachment in between, c) no cleft sutures, d) correction of subvalvular apparatus abnormalities, e) commissuroplasty. The repair of the partial form was obtained by: a) Valvular and subvalvular repair of the lesions when present, b) patch closure of the ostium primum defect suturing on the tricuspid side. All patients survived operation and exhibited normal sinus rhythm. Residual mitral incompetence proved to be less frequent as compared to previous techniques.