Successful correction of complete atrioventricular (AV) canal depends on accurate assessment of surgical anatomy and preservation of valve tissue to avoid postoperative valvular insufficiency. From 1975 to 1980 there were 68 patients aged 2 months to 17 years (median age 12 months) who underwent correction for the complete form of AV canal. Forty-six percent had associated anomalies which included patent ductus arteriosus, right aortic arch, pulmonic stenosis, and ostium secundum defect. Two types of repairs were employed: group I-Teflon patch closure of the ventricular septal defect (VSD) by division of the common leaflets into mitral and tricuspid components: Group II-Teflon patch closure of the VSD without division of common leaflets by fashioning the patch between the chordae tendineae and under the common leaflets. The atrial septal defect component was closed separately with pericardium or Teflon. Overall mortality is related to presence of (1) elevated pulmonary vascular resistance (Wood units greater than 4), (2) prior palliative operations, or (3) associated cardiovascular anomalies. Repair of complete AV canal without splitting the common leaflets preserves valve tissue. The act of splitting the common leaflets and reattaching the mitral and tricuspid components to the VSD patch by necessity sacrifices valve tissue. Although this may not be significant in older children, it becomes important in infants, for the sacrificed valve tissue comprises a greater proportion of the whole. Moreover, patch disruption of the reattached mitral and tricuspid components can be avoided if the common leaflets are not split.