We describe the clinical and necropsy findings of a newborn with trisomy 18 and atrioventricular canal. The patient also showed an aortic coarctation, a dysplasia of the common atrioventricular valve and multiple extracardiac anomalies. The atrioventricular canal, so frequent in patients with trisomy 21, is unusual in trisomy 18. The present case is the 6th of the medical literature.