Fetal echocardiography was performed using a high-frequency vaginal ultrasound probe in 114 singleton pregnancies between 11 and 16 weeks of gestation. The four-chamber view with both atria, atrioventricular valves and ventricles as well as the origin and double-crossing of aorta and pulmonary trunk could always be demonstrated from the 13th week onwards. In 12 of 13 cases, cardiac malformations were diagnosed in the first trimester. Only in one case was transabdominal echocardiography necessary at 20 weeks to make the diagnosis. In several cases, however, additional malformations were overlooked, in particular anomalies of the great arteries, such as coarctation of the aorta. Therefore, the accuracy of second-trimester transabdominal echocardiography is markedly higher. Because of the lower diagnostic accuracy, the high costs of equipment and the high training demanded of the examiner, first-trimester transvaginal echocardiography should be restricted to the high-risk fetus, i.e.: (1) Cases with other fetal anomalies very often associated with cardiac defects, such as nuchal edema and hygroma, non-immune hydrops, omphalocele, situs, inversus, or persisting arrythmia; (2) High-risk families with one or more first-degree relatives with cardiac defects are either inherited by Mendelian rules alone, or as part of a rare syndrome; and (3) In pregestational diabetes of the mother.Thus, many severe cardiac defects can be detected or excluded in the first trimester, reducing maternal anxiety. In these high-risk cases, second-trimester echocardiography using the transabdominal route should always be performed because of its distinctly higher diagnostic accuracy.