Thirty patients with complete atrioventricular septal defect were operated upon between 1989 and 1996 at our institute. Their ages ranged from two months to 24 years (mean age 2.81 years). All patients had severe pulmonary arterial hypertension except one who had associated pulmonic stenosis. Four patients had severe atrioventricular valve regurgitation and another six had moderate regurgitation. Five patients had Down's syndrome. The cleft in the left atrioventricular valve was closed in all but seven patients. There were five (16.66%) in-hospital deaths which included two patients in whom the cleft was left open. Follow-up ranged from three months to eight years. All patients were evaluated by 2D echocardiography in the immediate post-operative period and three to six monthly subsequently. One patient progressed to moderate and another to severe left atrioventricular valve regurgitation during follow-up. In both the patients the cleft had been left open. All other patients continue to have stable left atrioventricular valve status, that is, none or trivial to mild regurgitation. In view of late deterioration of the left atrioventricular valve regurgitation only in those patients where the cleft was left open, we suggest complete closure of the cleft in all complete atrioventricular canal defects.