Fetal blood sampling is accepted and widely practiced by experienced perinatologists. Its facile and safe access to the fetal circulation has broadened the spectrum of congenital disorders diagnosed prenatally. Some fetal disease states can now be identified and treated earlier, directly, more quickly, and more effectively than before, resulting in improved patient care. The volume of fetal blood to be retrieved and collection media for blood (Table 7) will be dictated by the indication for the procedure and thus the desired laboratory tests. These items and the preferred sampling site should be planned in advance by the operator. However, a flexible approach to fetal blood sampling should be maintained, anticipating the variability of fetal positions, cord insertions, and ultimate specimen volume. Teamwork among the perinatologist, sonographer, laboratory, and patient will continue to expand the role of fetal blood sampling in obstetrics.