We examined the frequency with which congenital heart disease (CHD) and cytogenetic abnormalities were found associated with omphalocele, gastroschisis, duodenal atresia and posterior diaphragmatic hernias. We performed fetal echocardiograms on 80 patients with these diagnoses and found congenital heart disease in 13 of 37 with omphalocele (35%), 2 of 17 with gastroschisis (12%), 4 of 15 with duodenal atresia (27%), and 2 of 11 with posterior diaphragmatic hernia (18%). Karyotypes were obtained in 74 and were abnormal in 24 (32%). Although most fetuses with these extracardiac malformations and abnormal karyotypes had associated CHD, many did not. Normal karyotypes were found in 69% of fetuses with CHD and omphalocele, and 50% of fetuses with CHD and duodenal atresia. We conclude that CHD may be present in fetuses with extracardiac malformations whether or not the karyotype is normal and that the prenatal evaluation of fetuses with these lesions should include both karyotype and fetal echocardiography. Although karyotypes play an important role in prenatal diagnosis, they are not predictive of normal cardiac structure when normal in the abnormalities studied. Even when the karyotype is normal in the presence of these abnormalities, fetal echocardiography is indicated.