We report on biometric measurements of the fetal heart with the TM-technique; these measurements were carried out between the 20th and 40th gestational week. The right and left endsystolic atrial and ventricular diameters were, measured, as well as the diameters of the large vessels, i.e. aorta and pulmonary artery; finally, the septal thickness was determined. Our measurements show a linear progression of the diameters in question, the right-left ratio of the atria and ventricles was close to one, so was the ratio between aorta and pulmonary artery. Our results are compared, as far as possible, to the literature.