OBJECTIVES: The purpose of this study is to test the possibility of the fetal cardiac intervention with tiny uterus incision in fetal sheep. METHODS: In our study, seven anesthetized pregnant ewes(105 to 120 days of gestation; term=145 to 150 days) were performed fetal intervention with tiny uterus incision approach. Two tiny incision(nearly 0.5cm) were performed in uterus to expose the fetus’s mouth and the fetus’s umbilical cord sheath, which allow fetal transesophageal echocardiography and umbilical arterial puncture. Monitored by fetal transesophageal echocardiography, we placed guidewires via the umbilical arterial route into the fetal heart. RESULTS: we advanced the 0.014-in guidewire into the left ventricle(n=4) and right ventricle through PDA (n=2). Access was not achieved in 3 fetuses because of bleeding complications (n=1) or because the setup through tiny uterus incision could not be established (n=2). All but 3 fetal sheep were alive at the end of the procedure. CONCLUSIONS: Direct fetal cardiac intervention by tiny uterus incision is feasible in fetal sheep. This new technique is easy to perform and is an alternative way for fetoscopic fetal cardiac catheterization.