Objectives: Human fetal cardiac intervention has typically involved a percutaneous transventricular approach. In fetal lambs, a transhepatic approach to access the fetal intra-abdominal veins after exteriorization of the uterus by laparotomy has been described. We aimed to develop a percutaneous transhepatic technique for catheterization of the fetal heart at mid-gestation that avoids maternal laparotomy. Methods: In 10 fetal lambs (90-97 days gestation), access to the fetal venous system was by percutaneous puncture with a 5Fr sheath (n = 1) into the umbilical vein or 16G IV-catheter (n = 9) into the hepatic vein. This was followed by cardiac catheterization using a 1.8-2.6Fr tapered coronary catheter. Euthanasia and postmortem examination were planned immediately post-procedure (n = 2), or after normal term-delivery (remaining cases). Results: In 1 case fetal position precluded procedural attempts, and in another, the fetus, accessed by a 5Fr sheath, died from umbilical haemorrhage. In 8 cases, access to the fetal hepatic vein was achieved. In 7 of these cases the access catheter was advanced into the IVC, followed by catheterization of the RA (all cases) and 4 cardiac chambers (3 cases). One fetus died during cardiac catheterization (RV perforation) and the other 7 fetuses were alive at the end of the procedure (88 survival). Immediate postmortem (n = 2) detected intraperitoneal bleeding (4 and 20ml respectively), while the postnatal postmortem (n = 5) after uneventful pregnancy revealed no vascular or cardiac trauma. Conclusions: Ultrasound-guided percutaneous transhepatic cardiac catheterization is feasible in mid-gestational fetal sheep. This technique has the potential for translation into human fetal cardiac and circulatory interventions.