In recent years, several fetal cardiac malformations such as hypoplastic left heart syndrome have been increasingly treated before birth with gradually improved outcome, although the technique is still invasive.We newly developed an automatic delivery system of high-intensity focused ultrasound (HIFU) with real-time 2D-ultrasound imaging analysis to correct cardiac morphologic abnormalities less invasively.The system could be controlled by a computer-based analysis of 2D-ultrasound left ventricular images for optimal HIFU deliveries.Using beating heart of four anesthetized adult rabbits, the system successfully achieved a non-touch gross ablation of the atrial septum in three animals, and in the other HIFU delivery was slightly mistargeted on the posterior wall of the left atrium with a resultant small transmural opening.We believe that the system will be introduced with pinpoint accuracy to minimally invasive fetal cardiac interventions that have intact or highly restrictive atrial septum.In addition for more reliability, we are now challenging to upgrade the system with 3D-ultrasound imaging analysis and variable focusing HIFU transducer.