From June 1977 to February 1986 we studied 31 children with dilated cardiomyopathy. Seven patients (22%) aged 8 months to 3 years had associated congenital cardiac lesions--tetralogy of Fallot (3), coarctation of the aorta (2), ventricular septal defect (1) and Ebstein's malformation (1). The diagnosis was confirmed by hemodynamic and angiographic studies in 5 patients and by autopsy in 2. Although different congenital lesions were present, all 7 patients had congestive heart failure, flattening of T-waves or ST-segment depression on the electrocardiogram and significant decrease in the left ventricular shortening fraction as judged by echo. We conclude that the incidence of dilated cardiomyopathy associated with congenital heart malformations is high in our pediatric population. The clinical status of patients appears to be more dependent on the improvement of dilated cardiomyopathy and less dependent upon the underlying congenital heart malformations.