The experiences in vaginal sonography in early pregnancy are reported and the first results concerning the dimensions of various structures in relation to gestational age are given. Intra-uterine structures can be identified and evaluated from a measured minimum diameter of 2-3 mm. Visualization of the chorionic cavity which proves an intra-uterine pregnancy, is possible with 4 complete weeks p.m. With 10 weeks p.m., it reaches a mean diameter of nearly 50 mm. The yolk sac which normally measures 4-5 mm and excludes a blighted ovum, is reliably seen from 5 to 10 weeks p.m. The embryo and its cardiac action which proves viability of the gestation, is recognized with 6 weeks p.m. With 10 weeks p.m., the crown-rump-length measures approx. 40 mm. Thus with vaginal sonography, the mentioned important parameters of early gestation are visible 1-2 weeks earlier than with abdominal ultrasound examination. Furthermore, other structures like amnion, umbilical cord, cranial pole of the embryo etc., can be identified earlier and in more detail. The corpus luteum is frequently recognized in the ovary as an echo-free structure with a more echo-dense border. If a non-viable early pregnancy is suspected, long hospitalization and expensive hormonal investigations are avoided by the early demonstration of a viable intra-uterine pregnancy.