Medical records of 118 newborn infants with Down's syndrome were reviewed to document the types of congenital heart disease (CHD) in those having echocardiography. Of 102 infants having echocardiography, 49 (48%) had heart defects; 47 of these had trisomy 21 and 2 had unbalanced translocation karyotypes. Of the 53 (52%) who did not have heart defects, all had trisomy except 1 with a mosaic karyotype and 1 with a translocation karyotype. The most common heart malformation was an atrioventricular canal, followed in frequency by ventricular septal defect, atrial septal defect, patent ductus arteriosus, and tetralogy of Fallot. Benefits of echocardiography in such infants are early detection of CHD, with aggressive management to prevent future complications, and reassurance to parents if the infant does not have CHD.