Short-term ultrasound-guided fetal umbilical cord catheterization in humans has been reported. However, before chronic umbilical vein catheterization is attempted in humans the technique must be tested in the non-human primate model. If the fetus was to tolerate this procedure, chronic fetal umbilical vein catheterization could be used for drug administration, parenteral fetal nutrition or to monitor the changes of hematologic parameters during and after open or endoscopic fetal surgery. In this study, 4 pregnant baboons were used to test the feasibility of ultrasound-guided umbilical vein catheterization. Although the umbilical vein was successfully catheterized in all the animals, only 1 fetus survived the postoperative period. The 3 immediate fetal deaths were due to a fetal intra-amniotic hemorrhage, while the most likely cause of death of the 4th animal was infection. In the surviving fetus and mother, blood was sampled once a day. Neither fetomaternal hemorrhage nor thrombosis could be documented. We conclude that ultrasound-guided transplacental umbilical vein chronic catheterization is technically difficult but feasible in the baboon model. Further studies in this model are needed to improve the catheterization technique and to monitor the extent of time that the catheter may be tolerated within the umbilical vein.