The application possibilities of abdominal fetal electrocardiography for pre- and subpartual continuous registration of the fetal heart frequency are examined. For this purpose the technical quality of 403 abdominal FEKG-registrations were checked in the individual stages of pregnancy and during birth. The average time spent looking for the best position with the greatest R-wave amplitude amounting to 2.6 min. The abdominal longitudinal position and the right hand oblique abdominal position proved to be advantageous with longitudinal presentation of the fetus. With fetal oblique to transverse presentation and in the 6th to 7th month of pregnancy the transverse abdominal position was likewise favourable. The technical quality of the supervision varied in the individual months of pregnancy. The best results were achieved in the 6th and 11th month of pregnancy. The worst technical quality was registered in the 8th month. In the 7th and 9th month two thirds of registrations were at least adequate. Sub partu the registrations during the first stage of labour were in two thirds of the cases very good and good, in a quarter satisfactory, in approx. a sixth adequate and fairly bad. In the second stage the registrations were considerably worse, 10.7% were satisfactory, 28.6% adequate and 59.8% deficient. Prepartually the technical quality was dependent on the fetal R-wave amplitude. In the second stage of labour no correlation between fetal R-wave amplitude and technical quality could be ascertained. The rupture of the amnion only influenced the quality of the registrations, if the satisfactory of labour increased. Adiposis and the position of the placenta did not affect the technical quality of the registrations. The lateral positions of the patient led to unusable registrations in 26.2%, in 46.9% the left and in 44.6% the right lateral position could be accepted without loss of quality. The comparison of the subpartual parallel registrations by means of phonocardiography/abdominal fetal electrocardiography, as well as direct/abdominal fetal electrocardiography showed no differences in the baseline. Differences in the floating-line in the case of simultaneous phonocardiography/abdominal fetal electrocardiography concerned the phonocardiographic registrations and in the case of simultaneous abdominal/direct fetal electrocardiography the abdominal registrations. They were caused by reduction in the technical quality. The fluctuation types of the abdominal and direct registrations were identical. In the case of simultaneous phonocardiography/abdominal fetal electrocardiography differences were found both in the oscillation amplitude and the oscillation frequency. The difference in the oscillation frequency was caused by a bad technical quality. The lower oscillation amplitude in abdominal fetal EKG-registrations was defined by the more exactly signal of the fetal R-wave...