Abstract Introduction: TTTS complicates from 10 to 15% of monochorionic diamniotic pregnancies. Expectant management is associated with 80 – 100% mortality. First in-utero intervention in the fetus with CHD was performed in 1991. However, only recently have they attained wider acceptance of cardiologists and perinatologists. Objective: Our main objective was to analyze the studies evaluating prenatal interventions in pregnancies complicated by TTTS or CHD, and to determine whether, given the available data, those interventions are justified. Methods: Pubmed and Cochrane database were searched for all studies related to in-utero interventions in fetuses with TTTS or CHD. Emphasis was placed on randomized controlled trials. Results: Meta-analysis published in Cochrane database concludes that laser photocoagulation of communicating vessels improves outcome in all stages of TTTS. Additional studies are required to elucidate the role of amnioreduction. For interventions in fetuses with CHD published data is limited to the case series. Potentially, selected patients with CHD would benefit from in-utero intervention, but additional studies are required. Conclusions: Prenatal interventions in TTTS improve the outcome. Further studies are required to define their role in patients with CHD. For all procedures selection criteria and indications for interventions need to be clarified. More precise prenatal diagnosis and improvements in the area of fetal monitoring during the procedure might positively impact survival. Preterm birth and premature rapture of membranes remain significant adverse outcomes. Complications associated with prematurity might counteract the positive effect of fetal intervention. Most cases of in-utero interventions should only be performed in specialized centers as a part of a clinical trial protocol.