Ultrasonic diagnosis is widely used today in obstetrics and gynecology. As no harmful side-effects, neither to the mother nor to the fetus can be detected, the method can be used to study the fetal development in its natural environment. The technics used for this study are either compound-scan or real-time scan. Progressing from the early to the late pregnancy the clinical problems, in which ultrasonic diagnosis is of importance are discussed. In early pregnancies these problems are related with the symptoms of abortion, whereby intact pregnancy, blighted ovum, missed abortion, ectopic pregnancy and hydatidiform mole, can be differentiated by ultrasonic examination. In advanced pregnancies ultrasonic examinations are used to achieve biometric data reflecting normal and abnormal progress in the uterine fetal development. Such data are the biparietal diameter and abdominal measurements such as diameter and circumferences which may be influenced by placental insufficiency resulting in growth retardation. The importance of the exact location of the placenta using echography as well as the possibility of the exact diagnosis of the fetal position are stressed. In gynecology echography can be used for monitoring the ovarian cycle in demonstrating the maturing follicle and the corpus luteum. Tumors of the genital organ can be differentiated to a certain extent. In the management of patients suffering from cancer, ultrasonography can be used for treatment-planning and in the follow-up study to detect local or lymphonodal recurrences as early as possible and to plan second-look operations.