Management of the left AV valve is the most crucial component of the repair of complete atrioventricular septal defect (cAVSD). A scarcity or deficiency of leaflet tissue may compromise satisfactory repair in a small number of patients with cAVSD, especially in patients with a normal karyotype. We describe the case of a 44-day-old baby who had cAVSD with severe left atrioventricular valve regurgitation due to dysplastic bridging leaflets. The repair was successfully performed by augmenting leaflet tissue and reconstructing the chorda using single patch. This technique could be one of the options in the repair of valves in order to avoid valve replacement in a small infant, although material of patch and reoperation need to be considered.