**Abstract**

Fetal therapy (in utero therapy) is a type of special therapy which aims to prevent or correct congenital anomalies in fetus, and prevents their severe consequences on later fetal development. It includes the use of in utero human fetal stem cell transplantation, fetal gene therapy and gene-editing technology as a new treatment for fetal genetic disorders. It started with open fetal surgery and then significantly advancing with innovations, toward minimally invasive fetal procedures, which are undoubtedly the future of fetal surgery, with the goal of providing the best possible fetal outcome, while minimizing the morbidity and mortality to the mother. The goal of fetal treatments is to decrease both fetal and maternal risks and prevent premature rupture of membranes. Fetal ultrasound and MRI are crucial for successful fetal interventions. Moreover, multidisciplinary fetal teams, including fetal surgeon, ultrasonographer, perinatologist, and anesthesiologist, are essential for optimum care to both mother and fetus. Finally, any new modality of fetal therapy must be thoroughly evaluated in animal models before clinical practice. In this chapter, we discuss the basic principles of fetal surgery, milestones of fetal surgery, specific fetal anomalies that are amenable for fetal surgery, successful fetal surgery criteria and future of fetal surgery.

**Keywords:** fetal therapy, in utero therapy, fetal team, minimally invasive fetal procedures
